Longevity Neuroscientist: Fix These 5 Things After 40+ To Preserve Muscle Strength & Stay Young!

Dr. Rangan Chatterjee 0:00 For people who, I guess, have a bit more time or are already active, let's say they're already able to go for a 30-minute walk seven days a week. They're like, "Tommy, look, I, I can do that. That's no problem. My, my life and my work allows me to do that. What else should I be doing as I get older to, you know, look after my health, body, brain, mind, everything?" Where would you go next?

Dr Tommy Wood 0:26 Resistance training of some kind. There's some kind of weightlifting or something where you're applying resistance to, to the muscles. I ... You know, there's lots of different ways that you can think about this. Uh, in general, um, I think there's a ... I have a pyra- a movement pyramid. It's my own movement pyramid. And, and I think at, at the, at the bottom is just spending less time sitting, right? So there's even, there's even benefits to, um, you know, getting a standing desk if you, if you can. Also, say, say you're in, you're in a job where you're sitting all day. Is there some way to make it so that you're just sitting less? And that could even be this idea of movement snacks where, you know, once an hour you go for a quick walk or you go up and down some stairs or wh- whatever you can do near you. So just less time sitting. Um, and then the next would be spend more time walking.

Dr. Rangan Chatterjee 1:21 Mm-hmm.

Dr Tommy Wood 1:21 And there's a whole bunch of studies, again, suggesting that brisk walking, um, particularly in those who are, who are otherwise sedentary, can dramatically improve, um, your health. And there's this linear benefit of number of steps you can get per day in terms of mortality risk and dis- and various disease risk up to maybe somewhere between 8,000 and 14,000 steps per day or something. But the more you can do in that 0 to 10,000 or 12,000, the better really. And a lot of that, particularly if you're doing

Dr Tommy Wood 1:51 quite brisk walking, so say you're doing your 30 minutes and it's quite brisk, um, then that for many people may be getting them up into that area that you mentioned, briefly mentioned earlier, that zone two. So you're getting some of those cardiovascular benefits, and that's probably where a lot of that benefit comes from. So then the next level I think is, is resistance training. Um, and particularly as you get older, we know there's a decrease in muscle mass, but more importantly, and probably faster and earlier, there's a decrease in strength. And as you get older, you lose, in particular, type 2 muscle fibers. These are our fast-twitch muscle fibers. And those are important for a number of reasons, because they're, they're an important glucose sink, so they're important for metabolic health, right? So if you're talk- we talked earlier about all these things that affect your blood sugar.

Dr. Rangan Chatterjee 2:39 Mm.

Dr Tommy Wood 2:39 Having healthy, active muscles and having a lot of these types of fibers is really important for our blood sugar control and a whole host of other things. Um, and it's also really important for our stability and mobility and function. So if you lose those fast-twitch fibers, those are the ones that are important for, like, reactions and, like, if you, uh, if you, like, are gonna fall, like grabbing onto a handrail or stopping yourself from falling.

Dr. Rangan Chatterjee 3:03 Mm-hmm.

Dr Tommy Wood 3:03 And, you know, particularly as you get older, you know, falls risks and, uh, broken hips and all that kind of stuff, you're gonna be protected against that if you have more of those types of muscle fibers. And those are the ones that you get through resistance training. They're the ones you develop I- in particular. You know, it, it affects all the mu- all of your muscle tissue, but those are the ones that you protect when you do that kind of resistance training.

Dr. Rangan Chatterjee 3:25 I wonder if we could just spend a bit of time trying to define resistance training. Uh, and the reason I'm asking this question is some people don't wanna go to the gym.

Dr Tommy Wood 3:33 Mm.

Dr. Rangan Chatterjee 3:35 And, you know, given that gyms are a relatively modern phenomenon-

Dr Tommy Wood 3:38 Mm-hmm

Dr. Rangan Chatterjee 3:39 ... and that humans have lived to pretty decent ages for a long period of time, I think when we say resistance training or strength training, we have to broaden it out beyond lifting weights in a gym.

Dr Tommy Wood 3:52 Yeah.

Dr. Rangan Chatterjee 3:52 'Cause for the people who love that, they love hearing it and go, "Yeah, I knew I was on it with strength training," right?

Dr Tommy Wood 3:57 [laughs]

Dr. Rangan Chatterjee 3:57 But for people who don't like it, it can be a bit confusing. So indoor climbing, running up hills, right?

Dr Tommy Wood 4:05 Yeah.

Dr. Rangan Chatterjee 4:06 You know, that's resistance against gravity. In your view, what counts as resistance training?

Dr Tommy Wood 4:16 So it, it can be ... It is, it's literally any movement where you're, you know, you're moving your body in space against, so against something that makes it harder than it normally would be for that movement, if that makes sense. Right. So-

Dr. Rangan Chatterjee 4:29 So, so carrying your shopping bags to your car or even to your home or ... Is that resistance training?

Dr Tommy Wood 4:35 Yeah. Absolutely.

Dr. Rangan Chatterjee 4:35 'Cause instead of walking, you're, you're carrying, right?

Dr Tommy Wood 4:38 Yeah. And we've talked previously about, so you mentioned the blue zones. And in the Nicoyan Peli- peninsula, they're not all down the gym all day, right? Um, but they are doing physical activity every day that includes things like carrying and lifting. Um, and so ... And you can translate that to your own activities of daily living, as we call it, right? So if you wanna be able to carry your shopping, um, then heavy shopping bags are resistance training. Um, and any time that you're moving your body, and so it could be squats just with your body weight, that's resistance training. Or, you know, you could do pushups, and it can be against the wall rather than against the floor. You know, that, that's resistance training. Um, and, and it can just be these daily activities, like lifting things into cupboards and carrying things around. Like, all of that counts. And particularly as you get older, you want to maintain those, you want to maintain those functions.

Dr. Rangan Chatterjee 5:34 Mm.

Dr Tommy Wood 5:34 So anywhere you can find an opportunity to move your body against some kind of resistance, that counts. The, the problem, you know, does become at some point you need to progress things.

Dr. Rangan Chatterjee 5:48 Mm.

Dr Tommy Wood 5:48 So in order for it to create ... Again, anything is better than nothing. But to create an ongoing stimulus, it has to be a l- I think it has to be a little bit challenging.

Dr. Rangan Chatterjee 5:59 Mm.

Dr Tommy Wood 6:01 You know, if you're just gonna... So, so maybe, uh, you do a few, uh, calf raises, squats, push-ups against the wall, a few bicep curls in the kitchen. Like, all of that stuff is great. Um, but at some point you have to make sure that you're, you, you would like to progress, you would like to be, you would like to get stronger, such that that is no longer enough, and then you have to find some way to make it a, a little bit harder. So th- I think there has to be a challenge component to it as well.

Dr. Rangan Chatterjee 6:27 So the pushup against the wall then has to be the pushup against the table.

Dr Tommy Wood 6:30 Yeah.

Dr. Rangan Chatterjee 6:30 And then the pushup against the chair.

Dr Tommy Wood 6:32 Yeah.

Dr. Rangan Chatterjee 6:32 And then a few months later, maybe pushup on the actual floor.

Dr Tommy Wood 6:35 Yeah, exactly.

Dr. Rangan Chatterjee 6:36 Um, and also I think I just wanna highlight, let's say yoga and Pilates, for example.

Dr Tommy Wood 6:40 Oh, absolutely. Yep.

Dr. Rangan Chatterjee 6:41 Because sometimes I feel that gets left out of strength training, and I think, uh, participants, uh, and teachers of those disciplines will often say, "Hold on, a lot of what we do is, is hard on the muscles," you know?

Dr Tommy Wood 6:55 Yeah.

Dr. Rangan Chatterjee 6:55 And there are plenty of yoga moves, for example, or Pilates moves, which I think do count as resistance training.

Dr Tommy Wood 7:00 Oh, yeah. I think they absolutely should be included, particularly for, for, for this kind of discussion. Um, that... I mean, there's a lot of yoga stu- You know, I, I'm relatively strong. There's a lot of yoga poses and things that I can't, I can't do. It's a different-

Dr. Rangan Chatterjee 7:14 It's different

Dr Tommy Wood 7:14 ... it's different, but it definitely counts as r- as, uh, as resistance, absolutely.

Dr. Rangan Chatterjee 7:19 Is there a next rung on your pyramid?

Dr Tommy Wood 7:22 Yeah. So then the, the next rung, um, is high, is sort of high, is high-intensity interval training, or HIIT. And the reason why it's next is because I think that... And again, this is for, um, this is not for elite sports performance. This is just for average people who wanna try and figure out how to, uh, separate out their time in terms of movement. And so you will get some cardiovascular benefit from your brisk walking and it... or it could be, it could be cycling or, or, or something, right?

Dr. Rangan Chatterjee 7:51 Yeah.

Dr Tommy Wood 7:51 It doesn't, it doesn't have to be walking, but I, I like walking 'cause anybody or most people can do it. Um, but then you do get some slightly... You know, if, if you then want to get into the physiological, biochemical nitty-gritty, you do get different adaptations to high-intensity training versus lower intensity training, right? I think in general, that idea of intensity times time is what's most important. But of course, different things happen at the cellular level when you do one versus the other. And so you can, you know... That, that's, that's a beneficial add-on, uh, on top of, say, resistance training if you're already doing some, some low level, uh, intensity movement. And then on top of that, um, you know, if you, if you really enjoy it, I think you can do very long periods of, of endurance training. But it, but, but I don't think most people need that if they're just trying to move as much as they, as they can in order to improve their health. So that's kind of the, that's the progression that I use.

Dr. Rangan Chatterjee 8:45 Yeah. So, so I really like that. Um, if someone's hearing that and, and says, "Okay, Tommy, look, I don't move much. I like that pyramid, but do I have to sequentially go up it?" Or for example, if someone goes, "You know what? I used to do some strength training while I was at school, but I haven't done it in ages and I quite fancy that," there's no reason why they can't start there, right, on your pyramid?

Dr Tommy Wood 9:08 No.

Dr. Rangan Chatterjee 9:08 They don't have to progress up.

Dr Tommy Wood 9:09 Yeah. And, um, what's, what's quite good about, say, say if you're going to the gym, is there's, there's a lot of... You start doing the other stuff as well. So when you're, when you're at the gym, you're usually not, like, sitting like you would in, in, in a chair at a desk or on the couch or on the sofa, and you're probably walking around quite a bit, right? You're, you're getting some of that, you know-

Dr. Rangan Chatterjee 9:30 Mm-hmm

Dr Tommy Wood 9:30 ... additional movement. And, um, there are some, some nice papers that talk about how particularly if you do weight training to what they call voluntary muscular failure, right? So you do a number of repetitions-

Dr. Rangan Chatterjee 9:42 Mm

Dr Tommy Wood 9:42 ... to the point where you can't do any more with good form. Even that has some cardiovascular benefits, right? So you're similar to maybe some, some lo- low, lower intensity, uh, aerobic training. So yeah, I think, you know, anywhere in that, there's, there's, there's a, um, there's a good entry point for you, I think is, is great, and that's always where I would want people to start. The reason why I have, like, very long, hard endurance exercise at the top is 'cause that's often where people start because that's where they assume they need to be in order to improve their health, right? If I'm gonna g- I need to go for a run, it needs to be hard, and I need to do it for an hour, or else there's no point in doing it. But actually that's, that's quite taxing on the body, and you don't necessarily get all the, the other benefits that you would from those other different types of, uh, types of training. So that's why I put it at the top.

Dr. Rangan Chatterjee 10:29 Yeah.

Dr Tommy Wood 10:29 But there's other, there's, there's lots of other places that people can enter, and again, anything that you can do that you enjoy and is sustainable, that's the p- place to start.

Dr. Rangan Chatterjee 10:37 And the only thing I, I guess I'd wanna add there is we forget sometimes that exercise and high intensity exercise can be a stressor-

Dr Tommy Wood 10:44 Yeah

Dr. Rangan Chatterjee 10:44 ... on the body. And what I've, I've often seen with certain patients is they have very high stress lives, go, go, go. And then the workout is also, you know, high intensity, a fast one-hour run. That is very hard on the body.

Dr Tommy Wood 11:02 Mm.

Dr. Rangan Chatterjee 11:02 And I've... I think, again, this is a much broader conversation, so we will have to save this for another time, but I do think we also need to think about how much is this exercise now taxing us?

Dr Tommy Wood 11:14 Yeah.

Dr. Rangan Chatterjee 11:15 And I certainly have found over the last couple of years, I've really been leaning more into a lot of low intensity, you know, walks or bikes or swimming where, you know, it's just nice and relaxed, but I'm going for 30, 40 minutes, maybe an hour. I'm like, wow, I, I feel like I need no recovery.

Dr Tommy Wood 11:33 Yeah.

Dr. Rangan Chatterjee 11:33 It doesn't stress me out. And I kind of measure it sometimes with HRV and heart rate variability and things like that, and I'm like, wow. I do feel that we sometimes forget about the stress components. So that's if people really wanna dive into it. But I, but I agree with the message, which is anything's better than nothing, and it's probably not that much for most people, right, that's gonna give them some benefits.

Dr Tommy Wood 11:53 Yeah. Uh, the main thing that I try and get across is that the dose needed or the amount you do needed to, to see some benefit, again, for, for most people is really quite low. And that the ... 'Cause, 'cause often what you see, and that's, that's kind of e- allu- what I alluded to earlier, is that people assume that they need some vast amount, several hours a week, in order to see benefit. And if, and if they can't do that, then they just don't bother doing anything.

Dr. Rangan Chatterjee 12:27 Okay. That makes-

Dr Tommy Wood 12:27 So the, the most important thing is to do more than you're currently doing, a- again, if you're relatively sedentary or you're, you know, trying to improve your health through physical activity. Um, and then, you know, once, once you get beyond that point and you have several hours a week to train, of course there's lots of different protocols and different things that you can follow. But up until that point, you know, anything that you can do and is sustainable and you enjoy is gonna be great.

Dr. Rangan Chatterjee 12:52 You've touched on muscle mass, uh, through the lens of resistance training and how important that is as we get older. We have spoken about it before. One thing I wanted to cover though is, like, if I look at you, you're a muscly guy. You know, you like to ... You know, you, you compete, I think, don't you, in-

Dr Tommy Wood 13:09 Yeah, in Strongman.

Dr. Rangan Chatterjee 13:10 In Strongman, right? So that's a passion for you.

Dr Tommy Wood 13:13 Mm.

Dr. Rangan Chatterjee 13:13 And you, you, you eat a certain way, you work out a certain way so you can compete in this sport. One thing I've been thinking a lot about over the last few months is, what's the cost of muscle? Because I don't feel that we see, often in these longevity hotspots, really muscly people, right?

Dr Tommy Wood 13:33 Mm.

Dr. Rangan Chatterjee 13:33 I haven't, I haven't gone out there and studied this in depth.

Dr Tommy Wood 13:35 Yeah.

Dr. Rangan Chatterjee 13:35 So I, you know, I, I can't say I know that for everyone or ... You know, we often don't hear about them being really muscly in their 40s and 50s. And I often think about a place that I spent a lot of time in, which is Chamonix in France, where it's in the mountains, in the French Alps, and m- many people there, if not most people, are active.

Dr Tommy Wood 13:53 Mm.

Dr. Rangan Chatterjee 13:54 They are, but very functionally active. So a lot of the time you'll see there people have got, uh, quite lean, um ... Th- They, they have, they have strong physiques, but not necessarily bodybuilding strong.

Dr Tommy Wood 14:07 Yeah.

Dr. Rangan Chatterjee 14:08 Uh, you see this with mountain guys and, and I think a lot about, okay, there's a big movement now to say, "Guys, you've got to work on your muscle mass as you get older."

Dr Tommy Wood 14:16 Mm.

Dr. Rangan Chatterjee 14:16 Because you're gonna lose muscle mass as you get older, and it's very important for longevity. It's important for brain health, as you've, you've covered, uh, before on the podcast. But we're not necessarily talking about big muscles, I don't think. I'd love you to expand on that and also, you know, I guess broad- broadly, you know, what is the cost of muscle mass? 'Cause the more muscle you have, I guess the more protein and calories you need to feed that muscle. So how do, how do you think about that?

Dr Tommy Wood 14:46 There's several moving parts that, that I'll try and, I'll try and cover. The first is, is an important one, um, which you didn't ask about but I will mention, which is that whenever I talk about muscle, everybody's like, "Well, I don't wanna look like you. I don't wanna eat like you. I don't wanna train like you." And that is not what I'm saying. Absolutely not. Um, and when I say that p- that people should build muscle mass and strength, I'm absolutely not talking about what I do or other, you know, other people do in terms of bodybuilding or s- or strength training. Um, that's completely separate. I don't think that that's detrimental to health, and we'll cover that as well, but that's not what I'm recommending to people.

Dr. Rangan Chatterjee 15:23 Mm-hmm.

Dr Tommy Wood 15:24 Um, a- and it's funny because I actually ... You mentioned Gabrielle Lyon, and, um, I heard, uh, like, a- an anecdote, which is that somebody, uh, somebody was telling me that they'd been telling their or suggesting to their wife that they should, um, may- maybe do some strength training, you know, for all the reasons that we talked about. And it was sort of like in one ear and out the other. Um, but as soon as she heard another woman like her talk about the importance of strength training, immediately that-

Dr. Rangan Chatterjee 15:53 Mm

Dr Tommy Wood 15:53 ... that, that message went in. So it's ... So the message is important, but the messenger is important as well. So-

Dr. Rangan Chatterjee 15:58 100%

Dr Tommy Wood 15:58 ... sometimes it's not good for me to talk about muscle because people are like, "Well, I don't want ... You know, that ... I, I don't wanna look like that." And that's obv- that's definitely not what I'm suggesting. Um, when you look at ... Again, so at the population level, we're gonna use that word again. So we do these large, large studies of people who sort of represent the population, and they've done it in the UK with the UK Biobank. They do it wi- in the, in the US with NHANES. And oth- uh, I mentioned earlier how terrible the NHANES dietary data is. The other data they collect in NHANES is actually very good. Um, and what you see is that those who are in the top 50% of muscle mass, so, you know, just above average, they tend to live longer, um, and have, uh, you know, an overall lower risk of most diseases and, and mortality. But there's not, like, a dose response. It's not like more is better.

Dr. Rangan Chatterjee 16:51 Mm.

Dr Tommy Wood 16:51 It's just don't ... So, so really the, the ... What you see from those studies is that low muscle mass being ... And, you know, we might use the phrase sarcopenia. That's the technical term for just having low muscle mass.

Dr. Rangan Chatterjee 17:03 Mm.

Dr Tommy Wood 17:03 Um, dynapenia is related to low strength, um, or loss of strength. So low muscle mass is, is problematic, um, rather than more muscle being better, if that makes sense.

Dr. Rangan Chatterjee 17:14 Mm.

Dr Tommy Wood 17:14 So you really just don't want to have not very much muscle. Like, that's where the real, um, signal of benefit comes from, again, at the population level. When ... You know, studies that I've done either ... And there's one we published just recently, and there's some other stuff that we're working on. Um, what we've found is that more muscle is not better, um, above a, you know, above that low level. But if you do have more muscle, it needs to be functional. So you need to have strength proportional to that amount of muscle mass. Um, and that's the kind of muscle mass that you generate through resistance training. So if I have more muscle but I'm stronger with it, I think that that is just fine. Right? That ... But there's another scenario where you can gain a lot of muscle, and that's ... This is muscle measured on a, on a, like, a DEXA scan, which is a type of X-ray scan. You look at how much muscle people have. And when they do that at the population level, those who have the most muscle, particularly in men, there was a, a p- a study that came out, um, from the UK Biobank recently. Those who had the h- the men who had the most muscle, the top, uh, it was either 20 or 25%, they had a higher risk of mortality and a higher risk of cardiovascular disease. But the men who were the strongest had the lowest risk. So there's this dissociation, that's another fancy word, like this separation of, like, strength and muscle.

Dr. Rangan Chatterjee 18:39 Mm-hmm.

Dr Tommy Wood 18:39 So strength is what's important relative to muscle mass. And when I've looked at some of these data myself, those ... You know, muscle does not correlate with physical activity. So these people are not gaining muscle because they g- they're in the gym all the time. They're gaining muscle because they're eating beyond their caloric needs and gaining more total mass, and some of ... And, and with that, they, they tend to have worse metabolic health, um, more, you know, uh, high blood pressure, worse blood sugar. Um, so they, they're not ... It's not muscle that's gained through lifting weights, right? It's muscle gained just through gaining more mass, and some of that is muscle tissue.

Dr. Rangan Chatterjee 19:19 So as people put on excess weight, there's an assumption that will always be fat.

Dr Tommy Wood 19:25 No, some of it is muscle.

Dr. Rangan Chatterjee 19:27 So you still put on extra muscle as well?

Dr Tommy Wood 19:28 Yeah, yeah.

Dr. Rangan Chatterjee 19:29 Wow. And actually, that relationship between strength and muscle reminds me of a conversation I used to have with a really good mate of mine who I was at uni with who was a, um, a very keen indoor climber. And he used to talk about the perfect ... You know, they'd measured the perfect ratio between strength and muscle for climbers.

Dr Tommy Wood 19:49 Yeah.

Dr. Rangan Chatterjee 19:49 Because you don't want too much 'cause then you're too heavy.

Dr Tommy Wood 19:50 Yeah.

Dr. Rangan Chatterjee 19:51 Right?

Dr Tommy Wood 19:51 Particularly in the legs. Yeah.

Dr. Rangan Chatterjee 19:52 Exactly.

Dr Tommy Wood 19:53 Yeah.

Dr. Rangan Chatterjee 19:53 And I was like ... So it reminds me of those conversations.

Dr Tommy Wood 19:56 Yeah. And I, I think the ... So there are, there are two parts to this. One is that there are, there are these studies, and you talked about the cost of muscle. There are these studies that suggest that more muscle is, is detrimental, but that's because muscle, you know, muscle is coming along for the ride with, um, you know, gaining excess weight and worse metabolic health and all that stuff that comes with it. That muscle has not been gained with a proportional improvement in strength or function. But if you look at having a high level of strength or function relative to your muscle mass, that's incredibly predictive of cognitive function and, and mortality risk. So you want enough muscle. You just don't ... You don't wanna have very little, and you want that muscle to be strong and functional. That's the most important thing, and that's, that's what you're talking about in terms of those, those individuals that you see, um, i- in the French Alps in, in terms of the, the individuals you see in, in longevity centers or, you know, you know, places around the world where people live a long time.

Dr. Rangan Chatterjee 20:50 It's functional.

Dr Tommy Wood 20:51 It's functional. Um, so whatever muscle that you have has to be functional. I think that's the main, that's the main takeaway.

Dr. Rangan Chatterjee 20:58 Now, related to that, Tommy, again, when- whenever we talk about anything, we have to think about in what population are we talking about it for.

Dr Tommy Wood 21:08 Hmm.

Dr. Rangan Chatterjee 21:09 And sometimes when I think about some of the protein research and the encouragement to high protein diets, I know we've covered that there's no real detrimental effects, and you, you believe in, as I do, that many people are undereating protein. And we think about it in terms of our muscle mass. Like, if you're not eating enough protein ... Let's say you sh- let's say you should be eating 30 grams for your, for your, for your size at a meal. Now, let's say you get really, really active and do loads of strength training. If you do that, yes, I know you need protein to support the muscle growth. But is there a case to say ... And I, I kinda think that maybe this happens in some longevity hotspots, that they are really, really active, maybe not eating high protein, but because they're so active and they're so functionally active, they're still maintaining muscle.

Dr Tommy Wood 22:01 Yeah. When you ... I think the, the best way to understand it in terms of the, say, the research that we have, is if you have individuals who are, um, calorie restricted, um, and when you restrict calories, one of the thing, right, you lose weight, and that comes from fat and muscle and, you know, o- other tissue as well. But in that scenario, if you add in physical activity, you preferentially keep that muscle tissue.

Dr. Rangan Chatterjee 22:33 Mm-hmm.

Dr Tommy Wood 22:34 And you'll, you'll preferentially get your, your energy elsewhere. So even if, you know, you have a, a period of time where you're e- either dramatically undereating or you have a, a high energy expenditure, um, then you will preferentially keep your muscle mass and strength as long as you maintain activity levels. So that becomes important if people decide to do long periods of fasting. Maintaining activity is important so that you preferentially keep ... You don't use your muscle tissue for energy. Um, and so that's, that's partly what-

Dr. Rangan Chatterjee 23:06 Hmm

Dr Tommy Wood 23:07 ... a part of what comes in there. But I think there's, there's also been a big debate in terms of ... So again, we go back, go back to the, the blue, the blue zones. There's, there's been some, some pretty reasoned debate in terms of how much protein those, those, um, groups are actually eating, and it is, it is probably more than the typical, uh, Western diet. You know, they're, they're not eating low protein diets. Uh-

Dr. Rangan Chatterjee 23:30 Hmm

Dr Tommy Wood 23:30 ... but then they're also physically active and all these other things that are important as well.

Dr. Rangan Chatterjee 23:33 I do remember, um, a conversation a few years ago. I was, I was speaking at a longevity conference, and Michel Poulain was there, who was one of the original researchers who went to study in the blue zones.

Dr Tommy Wood 23:48 Yeah.

Dr. Rangan Chatterjee 23:48 And he shared with me that, essentially that in some blue zones they're eating more animal products-

Dr Tommy Wood 23:56 Yeah

Dr. Rangan Chatterjee 23:56 ... than maybe-

Dr Tommy Wood 23:58 Than we've been led to believe.

Dr. Rangan Chatterjee 24:00 Yeah. I love a lot of the stuff on blue zones for sure. I think they're really, really interesting, but what their diet is, I, I, I'm not sure we're fully sure yet. [laughs]

Dr Tommy Wood 24:10 Yeah.

Dr. Rangan Chatterjee 24:10 Or certainly I've heard conflicting things.

Dr Tommy Wood 24:12 Yeah.

Dr. Rangan Chatterjee 24:12 Let's put it like that.

Dr Tommy Wood 24:13 Yeah. And when you step outside of those, um, you know, small pockets and you look at- Be more, say, uh, higher income or, you know, you know, Westernized, for want of a better word, societies. There are lots of populations around the world that eat a very high protein intake relatively and have some of the, the, the longest lived people on average. So like Hong Kong and Iceland-

Dr. Rangan Chatterjee 24:42 Mm-hmm

Dr Tommy Wood 24:42 ... eat a lot of animal products, a lot of meat, a lot of protein, and they are some of the longest lived nations on Earth. Um, so, so I think that using... You know, the blue zones are informative, but if you try and look at an overall population that's closer to, to ours in terms of overall technological, you know, development or, you know, and access to foods, then those, I, I think are worth considering as well. Um, and in general, you know, they... there are, there are several that, that have a high protein diet and, and, you know, live a long time.

Dr. Rangan Chatterjee 25:17 Yeah. I think also the nature of science often is to be reductive so we can measure one thing.

Dr Tommy Wood 25:22 Yeah.

Dr. Rangan Chatterjee 25:23 But our human experience isn't that reductive, right? We have all different kinds of inputs into our lives, and so I often feel that it, it c- it gets hard because, you know, science is very useful to inform us. But then... A- and I'm, I guess I'm biased from my experiences with patients where I kind of feel, yeah, that's one factor, but it kind of depends what are the other factors that are going on as well.

Dr Tommy Wood 25:48 Yeah.

Dr. Rangan Chatterjee 25:48 That influences how much that factor is important.

Dr Tommy Wood 25:51 Yeah.

Dr. Rangan Chatterjee 25:51 So thinking about food intake without also thinking about physical activity and stress and sleep, yes, can be useful, but potentially limited as well. So I, I-

Dr Tommy Wood 26:03 I feel, I feel like we over-focus on diet most of the time.

Dr. Rangan Chatterjee 26:06 So do I.

Dr Tommy Wood 26:06 That, that's, that's where everybody wants to go when all the other things that you mentioned probably for the vast majority of people are gonna be at least if not more important.

Dr. Rangan Chatterjee 26:14 Yeah. I, I totally agree. I mean, you've covered quite a lot, Tommy. I mean, maybe just one more topic.

Dr Tommy Wood 26:19 [laughs]

Dr. Rangan Chatterjee 26:19 Um, supplements. [laughs]

Dr Tommy Wood 26:22 [laughs]

Dr. Rangan Chatterjee 26:24 Um, you're a fan of creatine, aren't you?

Dr Tommy Wood 26:26 Yeah.

Dr. Rangan Chatterjee 26:27 Why?

Dr Tommy Wood 26:27 [laughs] Um, because it does everything. Now, it's, it's probably the one supplement that I would routinely recommend to pretty much everybody. Um, there was a, there was a recent study that came out in, uh, post-menopausal women where they took creatine, um, for two years, and it, it was ap- associated with some improvements in, in, uh, bone strength. You know, obviously, that's, um, uh, that's, that's, that's important for, for post-menopausal women. Um, I've... I'm a, I'm a big fan of it because of its effect on the brain. So, um, there are several studies showing that creatine supplementation acutely improves cognitive performance. Uh, that's in, like, in athletes, in young healthy people, and there have been large meta-analysis looking at creatine supplementation on cognitive function and, uh, the benefits are greater as you get older. So in those who are older, um, they, they have, they seem to have a great... they have a greater benefit. Um, there are studies where they've used creatine as an add-on to, uh, antidepressant therapy in those with major depressive disorder and seen a significant improvement above, uh, what, what they got in terms of the response from, from the antidepressant. And there are some, some studies suggesting that, uh, you know, the population level epidemiology, the amount of creatine that people get from their diets is associated with their, um, with their mood or risk of, um, mood disorders. Um, then there's the effect on strength that, you know, that in the majority of people, uh, creatine intake is associated with im- improved strength and, and, and muscle function. Um, so a wide variety of, um, uh, systems and organs in the body seem to benefit from, from adequate, uh, creatine intake. And not, um, it... the, the, the amount that you would take is, is maybe around something like 5 to 10 grams per day, and that's not, um, that's not a heroic dose [laughs] We'll go back to that term. Uh, relative to what you could get from the diet. So, a, a tin of sardines, um, is somewhere around 3 to 5 grams of creatine. So, uh, and, uh, 5 grams of creatine is probably, you know, it's like a kilo or two of salmon or, or beef, and like a n- not a lot of people eat that much salmon or beef. But it's, it's possible to, to eat that much from the diet, but just most people don't. Um-

Dr. Rangan Chatterjee 28:48 What is it?

Dr Tommy Wood 28:49 So it's, uh, um... it, it, it's, it's made out of three amino acids, and it's essentially... Well, it do- it does, does a number of things, but it, its main, uh, role is as, uh, an energy buffer. So earlier we talked about ATP, adenosine triphosphate, and when you move energy around the cell and you use it to do different functions with, with proteins and things like that, um, you do this in, with what we call high energy phosphates. So you break this bond with, with this phosphate molecule, and then that provides the energy for the process. When you, um, take ATP and you use up a phosphate, you create energy, uh, ADP, adenosine diphosphate. So it's gone from tri, which means three, to di, which means two, and then that needs to be recycled, and that's essentially what your mitochondria do. They're, they're recycling-

Dr. Rangan Chatterjee 29:52 Mm

Dr Tommy Wood 29:52 ... ATP or generating ATP. Uh, creatine creates a buffer for that system. So creatine, you put a phospho- a phosphate onto it. It's called phosphocreatine, and it's used to recycle, uh, ATP. Um, so it, it's kind of like this short term energy buffer.

Dr. Rangan Chatterjee 30:08 Sorry to interrupt. If you're enjoying this video and want to dive deeper into the topic of nutrition, I have created a free special guide which contains the five most important changes I think we all need to make when it comes to our diet. If you wanna get a hold of this free guide, all you have to do is click on the link in the description box below

Dr Tommy Wood 30:31 Um, and that's why it improves, um, physical performance. But some of the things that it improves in terms of cognitive performance, we're probably less sure about. Uh, it seems to have some effect on, uh, mitochondrial function and, and some other things. Um, it, uh, it integrates with the methylation system because, uh, producing creatine, w- and we make our own, um, is one of the most methylation intensive processes in the body. You know, by some accounts, the majority of methylation is used in order to generate and regenerate creatine in the body. So, you know, and then when you do that, you, you ... If you supplement with it, so you don't need to make it yourself, then you're offsetting the need for B vitamins and-

Dr. Rangan Chatterjee 31:15 Mm-hmm

Dr Tommy Wood 31:15 ... all these other c- these other, uh, nutrient requirements-

Dr. Rangan Chatterjee 31:17 Right

Dr Tommy Wood 31:17 ... you know, as part of the system. So there's a number of different ways that it ... And to be honest, we don't really know all of them.

Dr. Rangan Chatterjee 31:22 [laughs]

Dr Tommy Wood 31:23 We, we know it has these beneficial effects that we've tested in randomized controlled trials, but the exact mechanism by which that happens is still kind of up for debate.

Dr. Rangan Chatterjee 31:31 Quite cheap and accessible for people, is it?

Dr Tommy Wood 31:34 Uh, very cheap. Um, you ... You know, if people are gonna, are gonna buy it, they should buy something called, uh, creatine monohydrate. That's the, that's the cheap form that's been, um, well-studied, uh, i- in all kinds of populations for decades and decades. It's very safe. Um, most of it is made, uh, in Germany. Uh, it's a product called Creapure, and then they do what they call white labeling. So, uh, a sport supplement company-

Dr. Rangan Chatterjee 32:00 Mm

Dr Tommy Wood 32:00 ... just, like, buy ... or buys it in bulk and then puts their own label on it, and it's the same thing. And so just, like, a s- a scoop of one of those. And it can also be, um, useful ... If you're gonna buy supplements, in general, there's some due diligence that I would alwa- always recommend that people do. So, um, there are third-party testing companies or, or groups that test for impurities, and that can be important if you're a, a drug-tested athlete, but also for other things that you don't necessarily want to be in your supplements. So things like Informed Sport, you can see that as a stamp, uh, on your supplements. Um, and then often companies will say that they're batch tested or third-party tested. That means that they're making sure they're not full of heavy metals and these other things.

Dr. Rangan Chatterjee 32:43 Mm.

Dr Tommy Wood 32:43 Um, because, you know, some supplements, you know, particularly cheaper ones or you don't know where they, where they came from, they're made in some anonymous factory somewhere and who knows what's in them and, you know, wouldn't recommend that people take those. So you can, you can often ask for certificates of analysis, so h- you know-

Dr. Rangan Chatterjee 33:00 Yeah

Dr Tommy Wood 33:00 ... where people have tested for impurities and stuff like that. And I, I think that if people are gonna take supplements, it's worth doing that little bit of due diligence. But in general, if you see Informed Sport or something else, and, like, you can go to Holland & Barrett and you can buy an Informed Sport certified creatine monohydrate. Uh, it's very cheap. You know, anybody can do that, and you don't need to spend a whole bunch of time doing research on it.

Dr. Rangan Chatterjee 33:19 Uh, and I think that brings up a, a wider point on supplements. W- And I think one of the reasons why the medical profession for many years has been quite anti-supplements is because of the lack of regulation.

Dr Tommy Wood 33:31 Yeah.

Dr. Rangan Chatterjee 33:31 So there are poor quality supplements-

Dr Tommy Wood 33:33 Yeah

Dr. Rangan Chatterjee 33:33 ... out there for sure, but there are also high quality ones.

Dr Tommy Wood 33:36 Uh-huh. Yeah.

Dr. Rangan Chatterjee 33:36 And I kind of feel the whole thing, supplements good or bad, is a, is a ridiculous question in and of itself. It's like are pharmaceutical drugs good or bad? Well, kind of depends.

Dr Tommy Wood 33:47 Yeah.

Dr. Rangan Chatterjee 33:48 F- for who?

Dr Tommy Wood 33:48 Yeah.

Dr. Rangan Chatterjee 33:48 In what dose?

Dr Tommy Wood 33:49 Yeah.

Dr. Rangan Chatterjee 33:50 Uh, f- for how long for? And I personally have seen the right supplements be very beneficial for patients over a number of years. Um, so I have a slight ... I don't really share that view that's been there in medicine for a number of years, which is, you know, we sh- you know, stay away from supplements. Because we routinely give them, like, B12 as a supplement [laughs]

Dr Tommy Wood 34:12 Yeah

Dr. Rangan Chatterjee 34:12 ... or vitamin D as a supplement.

Dr Tommy Wood 34:13 Yeah.

Dr. Rangan Chatterjee 34:13 And we ... You know, so I, I don't kind of ... Yeah. That, but there, there's a bit of nuance there, and as you say, if you're gonna get one, get a high quality one.

Dr Tommy Wood 34:19 Yeah. And in terms of other, other supplements, in general, um, the, the vitamins b- like, come very ... like, and those who need them come very high on a list of things that I would recommend. So, um, vitamin D, uh, very important. Some of the B vitamins, very important. Some, um ... I think we measured ... I talked previously about measuring something like a homocysteine-

Dr. Rangan Chatterjee 34:43 Mm

Dr Tommy Wood 34:43 ... if you can, particularly if you're thinking about, uh, both brain health but then also cardiovascular health. And B vitamins that are relevant for that are RB12, folate, B6, uh, B2, which is riboflavin. And you can, you can get these from a ... right? If you're eating, uh, some green leafy vegetables and, um, some eggs and meat, you'll get a lot of those.

Dr. Rangan Chatterjee 35:05 Mm.

Dr Tommy Wood 35:05 Um, but equally, we know that being deficient in those is associated with a whole host of chronic health conditions. So, you know, I think we should ... You know, at the, in terms of within the NHS, we should probably do, be doing a little bit more testing for those things so that they can be, they can be supplemented if, if needed.

Dr. Rangan Chatterjee 35:22 Yeah. Homocysteine I still think isn't routinely available-

Dr Tommy Wood 35:25 No

Dr. Rangan Chatterjee 35:25 ... in the NHS. It's still a serum B12 and, um, you know, this whole thing about promoting diet and lifestyle first, yes, of course, but we also acknowledge in this conversation how tricky it can be for people to eat well.

Dr Tommy Wood 35:39 Yeah.

Dr. Rangan Chatterjee 35:39 And that's why, yeah, I'm all for a food first approach, but at the same time, I recognize that many, straight most people, are finding it hard [laughs]

Dr Tommy Wood 35:49 Yeah

Dr. Rangan Chatterjee 35:49 ... to get the nutrition they need. There's ... I don't know if you've seen this research on soil quality and how that's poorer now, and so are we getting the same level of nutrients that we were getting 50 years ago-

Dr Tommy Wood 35:58 Yeah

Dr. Rangan Chatterjee 35:58 ... from the same foods? That's really interesting. Also, I've tested, um, B12 a number of ways over a period of years, and I've been really quite surprised by how many people have suboptimal B12 levels.

Dr Tommy Wood 36:15 Yeah.

Dr. Rangan Chatterjee 36:15 Even animal food eaters. And I think a lot of that may also come down to the chronic stress in society, 'cause we need good stomach acid to absorb B12 if it's going through our gut and into our stomach, and one of the things that chronic stress will do is alter levels of stomach acid, alter how your digestive function is. I've got a friend who has tried everything. She used to be paleo, she was vegan, she was raw food. She's very educated on health. She's a practitioner. And about five years ago, she pretty much moved to close to carnivore, and I don't know many people ... She's in her 50s. She is thriving. She looks great. She can run ultramarathons. Um, I've done stuff with her. I've seen her work. She can work for 14 hours straight. Cognitive function completely just as good at 9:00 PM as it was at 7:00 AM. It's phenomenal to see. But I'm thinking if we take a step back for a minute, there are so many reports of people thriving on these animal-heavy diets. Autoimmune symptoms going, joint pain going. Like, we can either put our head in the sand as a profession and go, "No, you've got to do this. You've got to eat more fiber," or go, "Wait a minute. Well, what's going on here? Why are s- people not following the dietary advice and are thriving?" And she's also done all her blood tests. Her triglyceride to HDL ratio is fantastic. Her HbA1c's amazing. What's your perspective, Tommy?

Dr Tommy Wood 37:52 So I completely ... You know, o- o- on the gut front, and again, I, I know people who are much smarter, and know much more about this than, than I do, so I've, I've learned a lot from them. One of them is, uh, Dr. Lucy Manning, who I wrote this, this paper with. Um, and I think the gut has really been this thing where the more we know, the more we realize we don't know. Um, and again, the, the, the paper we wrote tried to come at this from, like, a, a first principles idea, which is that ... So if you think about the wide variety of, of environments and diets that humans thrived in and thrived on, how common is it, how common would it have been for you to have 30 different plant foods in your diet in a week, right? You're in Greece. Two things are in season, tomatoes and aubergines. You talked about that, right? What are the other 28 that you're supposed to find in the environment? Like, it's just not something that our guts ever, you know, are used ... quote, unquote, "used to seeing." That doesn't mean it's bad, right? I'm not saying that it's bad.

Dr. Rangan Chatterjee 39:01 Yeah.

Dr Tommy Wood 39:01 I'm just saying, like, what are the things that, you know, our guts have helped us through in the past? And if you think about it that way, then you have to think about scenarios when, like, there were no plants, right? So, so, you know, we've come at it from this idea that, uh, for the gut, plants are essential. Fiber is, fiber is essential. And that's pretty much because in large population studies, um, we've told people that that's the case. So people who are more health-conscious do that, but they also don't smoke, and they sleep more, and they exercise more, right? The healthy user bias. Um, and if we think about our guts and, you know, the rest of the body is the same. But in a healthy individual, it's, it's adaptable to many different types of fuel, right? Um, is it blood glucose, or is it fat, or is it ketones, right? These dif- these different, um, sources of energy that you can use, that you need to run your heart, or your muscles, or your brain. Your gut is the same. And the traditional story is that you need fiber, that your gut bugs turn to something we call short-chain fatty acids like butyrate. That provides the fuel for your, um, enterocytes, the cells in your gut. But what you see quite clearly is that your gut can use a wide range of fuels. So yes, it can use those. If, uh, if you eat predominantly plant foods, you'll make short-chain fatty acids like butyrate. That will, that will be the source of fuel. But if you eat more protein, then you'll make what we call iso short-chain fatty acids, and those essentially have the same function. So you can support your gut health just fine with the metabolites from meat rather than plants. The gut, the gut cells will still use it. Uh, you can also use acylcarnitines, which are metabolites of fats. Um, or if you're on a ketogenic diet, the, the ... It doesn't come from inside the gut like those other things do from the gut bugs. It can come from the blood. So you can take ... The, the cells in the gut can take ketones from the blood. If you're fasting or, um, you know, fasted because there's no food available, right? If there's no food available, your gut still has to be able to survive. It can't just, like, give up and stop working.

Dr. Rangan Chatterjee 41:08 Mm.

Dr Tommy Wood 41:09 Right? Because as soon as you get food, it needs to function. So then if you're, for whatever reason, don't have access to food, your body makes a bunch of ketone bodies, and the gut can use those for energy as well. So the gut is incredibly metabolically flexible based on the systemic health of the body and physiology of the body. So what I think we've seen in a lot of studies around the gut is that something that affects systemic physiology affects the gut, and then that affects the types of microbes that get selected for within the gut. So-

Dr. Rangan Chatterjee 41:43 Let's, let's just back up. Systemic physiology, what ... how would you say that in layman's terms?

Dr Tommy Wood 41:47 Yeah. So, so basically, your general health, right, and other parts of the body.

Dr. Rangan Chatterjee 41:49 So, so you do something that's affecting your general overall health.

Dr Tommy Wood 41:53 Yes.

Dr. Rangan Chatterjee 41:53 That's then affecting the health of your guts.

Dr Tommy Wood 41:56 Yes.

Dr. Rangan Chatterjee 41:57 And then you're measuring bugs in there, and we're make ... We're drawing conclusions from that.

Dr Tommy Wood 42:03 Exactly. And it's, uh, it goes in both ways. So we know that the bugs in your gut can affect your body. But it really seems like what's happening in your body elsewhere, and that can happen with changes in sleep, or diet, or physical activity, right? So when you exercise, that affects your general health. It affects what happens in your heart, and your blood vessels, and your muscles. They, you know, secrete a bunch of, um, chemicals and hormones and things like that. That can af- that affects your health. It also affects your gut. And then what happens is your gut is affected by that, by, just by your health changing. That then changes the kind of bugs that survive in that gut. So you'll see things change within the gut, right? You'll see different bugs, but it's because of what's happening elsewhere in the body.

Dr. Rangan Chatterjee 42:51 Hmm.

Dr Tommy Wood 42:52 So I think we've ascribed too much to the bugs that we measure, and it's also the bugs we can measure.

Dr. Rangan Chatterjee 43:00 Yeah.

Dr Tommy Wood 43:00 There's a whole bunch of stuff that we're just not able to measure, and this has been another problem with, um, studying the gut microbiome is that historically we've used, um, a, a cheaper measure called, um, looking at something called 16S RNA. Um, and when I've talked about this, um, previously, it ... the level of information it gives you is it's like if you think about the lineage of dogs, right? There are animals, and then canines, and then the, the sort of the, the house dog-

Dr. Rangan Chatterjee 43:31 Mm-hmm

Dr Tommy Wood 43:31 ... the dog that we have, dogs that we have at home. So a 16S RNA can tell you this is a dog rather than a cat, but it can't tell you whether it's a French d- bulldog or a Doberman, right? Which are vastly different dogs.

Dr. Rangan Chatterjee 43:43 Mm.

Dr Tommy Wood 43:44 And it's the same thing with gut bugs. So it might tell you, "Yes, I think I have an idea what this bug is," but it tells you nothing about its specific functions. Um, and a lot more about what's happening in the gut is based on the function of the bug rather than what the bug is.

Dr. Rangan Chatterjee 43:57 Yeah.

Dr Tommy Wood 43:57 And so vastly different bugs can have the same function, but you might just focus on one that has a specific function and think we need this, when actually something else entirely could take that function. So it's ... d- the information that we have is incomplete. Um, I think we've ascribed too much, um, you know, too much to its-

Dr. Rangan Chatterjee 44:17 Yeah

Dr Tommy Wood 44:17 ... to its activity. Doesn't mean it's not important. I think it's very important.

Dr. Rangan Chatterjee 44:20 No, for sure.

Dr Tommy Wood 44:21 But I, I think we've given it too much credit and, and taken away what's maybe happening elsewhere in the body at the same time.

Dr. Rangan Chatterjee 44:26 And also, maybe it's not even giving it too much credit, but it could also be, you know, we're overly focusing on lifestyle change influencing the gut microbiome, influencing our overall health. Maybe it's just the lifestyle change [laughs] is influencing our overall health, as you say, which is then influencing the gut microbiome.

Dr Tommy Wood 44:48 Exactly. Exactly.

Dr. Rangan Chatterjee 44:49 And this is one of the key things I think I've evolved my view on, uh, over the past few years, is this maxim that we need fiber for optimal health. I, I, I don't know the answer to that. I've just ... I'm very open-minded, and I, I just ... I can't, um, make that work in my head cognitively, and also see many, many people thriving, literally thriving in every way that I can see on low fiber diets.

Dr Tommy Wood 45:31 Yeah.

Dr. Rangan Chatterjee 45:32 I think it doesn't add up. Like, we've got to do better. Like, there's, there's ... Do you know what I mean?

Dr Tommy Wood 45:36 Yeah. And, and, and again, um, I think when we, when we've looked at ... So I'm, I'm not gonna say that fiber isn't important because I think in, in the, in the setting of the, the modern mixed diet where most foods are ultra-processed, and we think about the things that we talked about earlier that may be able to, you know, help support gut function, you're probably not getting any of those, and in that setting, fiber may be beneficial.

Dr. Rangan Chatterjee 46:05 Mm.

Dr Tommy Wood 46:05 It's also, uh, fiber in the diet when we ask people about their diet, it's like a marker of a bunch of other things.

Dr. Rangan Chatterjee 46:11 Yeah.

Dr Tommy Wood 46:11 Like, usually if you're eating more fiber, you're eating high quality foods. Um, and fiber may affect things like satiety, right? So if you're eating more fiber, then maybe you eat total fewer calories in an environment-

Dr. Rangan Chatterjee 46:22 Yeah

Dr Tommy Wood 46:23 ... that encourages us to eat more calories than we need. So there are these signals that maybe it's beneficial, but that doesn't mean that it's essential.

Dr. Rangan Chatterjee 46:29 Yeah. And, and just to, just to clarify my own view, I'm also not saying fiber is not important.

Dr Tommy Wood 46:34 Yeah.

Dr. Rangan Chatterjee 46:35 There is plenty of research which is suggesting that more fiber is associated with better health outcomes. I've written about this before, right? So I'm, I'm just ... I think we always need to remain open-minded.

Dr Tommy Wood 46:46 Yeah.

Dr. Rangan Chatterjee 46:46 And go, just 'cause we believe this to be true, just because everyone said it was true, maybe it's a partial truth.

Dr Tommy Wood 46:53 Yeah.

Dr. Rangan Chatterjee 46:53 Maybe, maybe it's true for a lot of people. And also, the other thing I think with diet, Tommy, is that when we look at these ancestral populations, these hunter gatherer tribes, and we look at what they're eating and, you know, the Hadza tribe in Tanzania are reported to eat a ton of fiber, maybe 100, 150 grams a day. I've seen in some reports compared to, you know, an urban population, a Western population that may be struggling to get 15, 20, 25 grams a day, right? So I get that on the face of it, it seems like a huge difference, and hey, we want their health outcome, so let's do that. Let's increase the fiber. But it also depends, doesn't it? That diet on top of what?

Dr Tommy Wood 47:39 Yeah.

Dr. Rangan Chatterjee 47:40 So if you've grown up there with low stress, eating naturally in sync with the seasons, you know, without the, the urban Western societal pressures that, you know, affect all aspects of our physiology, well, maybe that diet works really well. But maybe, maybe in the, you know, the world in which we, we live, you live in America now, I live in the UK, but so many people have got poor metabolic health already. They're already, um, got suboptimal health, so maybe they need a corrective diet.

Dr Tommy Wood 48:16 Yeah.

Dr. Rangan Chatterjee 48:16 Do you know what I mean?

Dr Tommy Wood 48:17 Yeah.

Dr. Rangan Chatterjee 48:17 It's kind of like ... And I, I sort of hypothesized in my first book why a low carb diet seems to work so well for so many people in the Western environment. Might be because we're overly stressed, we're underslept, we're, uh, undermoved, we're ... We've had too many calories or the wrong types of calories. We, we are insulin resistant, and therefore maybe in that setting there's a, there's a kind of unique role for it.

Dr Tommy Wood 48:43 Yeah.

Dr. Rangan Chatterjee 48:43 I, I don't know. I mean, I'm not saying I've got the answers or I'm ... I don't think you were saying you've got the answers either, but- It's worthy of discussion

Dr Tommy Wood 48:51 Yeah. Um, in, in my mind, uh, there's this, you know, every, every, everything that we use to describe human health, everything we use in biology is some kind of model, right? Um, and because we can't ... We c- we're unable to completely explain everything, right? It's not physics. And even in physics, they can't do that. Um, but there's this fam- uh, George Box is a statistician, has this famous quote, which is called ... which says, "All models are wrong, but some models are useful." And I think that's, that's really ... and I, I think that's really important to think about, 'cause everything we're th- we're talking about here is some kind of model to, to describe human health. And if your model doesn't allow for the individual that is doing amazingly well eating nothing but beef, then your model is wrong, right? It ... Then it's more wrong than any kind of model you can build that enc- that build that, that-

Dr. Rangan Chatterjee 49:50 Yeah

Dr Tommy Wood 49:51 ... encompasses that. So I always think, like, the outliers are important because they force you to change the parameters-

Dr. Rangan Chatterjee 49:58 Yeah

Dr Tommy Wood 49:58 ... of your model. And if you don't, I think that's incredibly unscientific. So yes, you can say, "That's interesting. I wanna learn more about that." But at some point you then have to try and incorporate it into whatever model it is that you're building that says, you know, well, why is it that we're seeing the ... You know, if humans can thrive in a scenario where they're not eating any fiber, then that has to be incorporated into the model somehow.

Dr. Rangan Chatterjee 50:19 Yeah. Yeah, I love that. I love that. Muscles, right? We've, we've drawn an analogy, you've drawn an analogy early on about muscle health and brain health.

Dr Tommy Wood 50:29 Yeah.

Dr. Rangan Chatterjee 50:30 And I'm really interested as to practically what advice would you give to people who want to optimize their brain health in terms of, yes, physical activity, but, but I guess specifically I'm interested in, in muscle. Um, I know, you know, you lecture on this. You, you're gonna give a talk I think this weekend-

Dr Tommy Wood 50:54 Yeah

Dr. Rangan Chatterjee 50:54 ... on, on muscle mass and longevity-

Dr Tommy Wood 50:56 Uh-huh

Dr. Rangan Chatterjee 50:56 ... in the UK, which you're here. We had Dr. Gabrielle Lyon on recently. She was talking, um, about protein intake, uh, the importance of resistance training. I would love your perspective on these things.

Dr Tommy Wood 51:11 So I obviously haven't heard your interview with, uh, with, uh, Dr. Gabrielle, but I imagine that I will have agreed with pretty much everything she said. So you can hear what I say, and then you c- because, in general, I, I, I think she's, she's, she's fabulous and she f- she focuses on, on really important things, which is muscle tissue and protein intake. Um, and the re- I, I mean, there are multiple reasons why muscles are important. They're our biggest glucose sink. So we talk about blood sugar, you talk about, you know, that being important for diabetes risk, but also cardiovascular disease risk, uh, dementia risk. 75% of your blood sugar is taken up into your muscles, and the more muscle you have and the more you move it, the more glucose blood sugar that they take up. So if you're trying to regulate your blood sugar, which is relevant to the vast majority of, of adults, 'cause they probably, you know, again, the average individual at least has pre-diabetes, average adult in, in the US and the UK and, and similar studies have been shown, shown that in Europe.

Dr. Rangan Chatterjee 52:08 That's pretty alarming.

Dr Tommy Wood 52:09 Yeah. And so, so I think the, the projected number in the US is 60%, um, have at least pre-diabetes, or obviously if you progress, then that includes pre-diabetes and frank type 2 diabetes. 60% of US adults.

Dr. Rangan Chatterjee 52:23 Currently or-

Dr Tommy Wood 52:24 Currently

Dr. Rangan Chatterjee 52:25 ... and do you know what that figure is in the UK?

Dr Tommy Wood 52:27 Um, I believe it's 40 or 50%.

Dr. Rangan Chatterjee 52:31 Yeah.

Dr Tommy Wood 52:32 So muscles are your most important glucose sink if you want ... right, if you wanna regulate your blood sugar, you need to create somewhere for that blood sugar to go, right? Um, and muscles are the thing. Uh, 75% of blood sugar goes up into, into your muscles.

Dr. Rangan Chatterjee 52:46 So the more muscle you have-

Dr Tommy Wood 52:48 Yes

Dr. Rangan Chatterjee 52:49 ... the easier it is to regulate your blood sugar.

Dr Tommy Wood 52:51 Absolutely. And the more you move it. So, and so both are important, right? So the total mass and then how much movement you h- uh, the, the amount that you move it. Um, and there are, there are several studies that have shown that. But you can, in, you know, again, in type 2 diabetics, you can put on continuous blood sugar monitors or look at their, you know, blood sugar, and the more they move, the better their blood sugar is controlled. Um, and if you have more muscle and you move it more, you can control that even better. So that's one reason why muscle is important. It's also, um ... It's a, it's an organ. Like, it secretes factors and hormones and things that we're still learning about, right? Um, every month there's a, another paper in a fancy journal that says, "We just learned this thing that happens when you exercise, and it makes this molecule, and then we inject that molecule into mice, and they live longer."

Dr. Rangan Chatterjee 53:41 That speaks to what you just said about the gut, right?

Dr Tommy Wood 53:43 Yeah.

Dr. Rangan Chatterjee 53:43 How long have we been studying muscles compared to how long have we been studying the gut? Years.

Dr Tommy Wood 53:48 Yeah. Decades.

Dr. Rangan Chatterjee 53:48 Decades on muscles, and we're still learning new stuff that we're like-

Dr Tommy Wood 53:51 Yeah

Dr. Rangan Chatterjee 53:51 ... "Oh, we didn't realize."

Dr Tommy Wood 53:52 Yeah.

Dr. Rangan Chatterjee 53:52 So it's kind of naive on the gut.

Dr Tommy Wood 53:54 [laughs]

Dr. Rangan Chatterjee 53:54 It's, it's like after 10 years of study, we kind of know all this stuff.

Dr Tommy Wood 53:57 Yeah, e- exactly. And so one of the reasons why I like to use exercise as an example is because everybody rec- right, diet we can argue about. Some other things we can argue about. Nobody argues about physical activity, right?

Dr. Rangan Chatterjee 54:09 Yeah.

Dr Tommy Wood 54:10 Everybody recommends it. Every health body, every governmental org- organization, every non-governmental organization says you should, you should move more, right? Physical activity is good for your health. But we don't know how it works yet. I mean, we know lots of things, but we don't know all of the things that happens w- happens when you exercise. And so what ... You know, it's a ... Um, when you, when you exercise, you release a whole bunch of factors that sup- you know, directly support the brain, things like brain-derived neurotrophic factor. You secrete things that decrease systemic inflammation. Um, a whole wide range of things. So it's this ... it's a secretory organ occ- you know, just like, um, just like the, the, the pancreas or the thyroid. Um, b- but, uh, when you move it. Um, and then sort of more practically As you get older, we, we know that you lose muscle mass as, as you age, and it particularly starts to decline from about 60, muscle, muscle mass. So it starts slowly in your 30s, and then it really accelerates when you hit about 60 on average. But strength declines pretty much continuously from your 30s. So you lose strength more th- you know, more, more quickly than you lose muscle tissue. And strength is really the thing. Like, functional, um, functional capacity of muscle is, is, is really important. It's like saying you don't want a bigger brain, you want a brain that works better, right?

Dr. Rangan Chatterjee 55:26 Mm-hmm.

Dr Tommy Wood 55:26 Like, that's the ... The function is the important thing, and, uh, strength is a really important predictor of mortality and, uh, cognitive decline. And there are simple things like if you have enough muscle mass and enough strength, then you're not gonna fall over, you know, and break a hip. And, right, if you get into your s- if you get into your 70s or 80s, you fall and break a hip, you have a very high chance of dying-

Dr. Rangan Chatterjee 55:49 Mm-hmm

Dr Tommy Wood 55:50 ... within the next, well, even days, then also weeks and months afterwards. So, like, your muscle tissue supports pretty much, you know, all the ... all, all these important ... Like, it supports every other organ in the body. Um, and what's int- what's interesting to me about exercise, particularly when you think about lon- lo- like longevity and aging, um, there was a ... Uh, about 10 years ago, there was a paper that came out called The Hallmarks of Aging, which are all these things that you can measure biochemically in cells that happen as the, as the body or the cell ages. Physical activity and exercise is the only thing that reverses all of those components. Like, it's the only thing that can actively anti-age you in everything that happens as you age. Um, so it, it, it basically, uh, affects everything. And then I know it's important to give practical advice, right? How, how ... Well, like, what's ... how much is enough? And, um, you know, whenever I talk about muscles, I have to ... you know, m- I have a phil- philosophical conflict, which is, like, I really like lifting weights, right?

Dr. Rangan Chatterjee 56:55 [laughs]

Dr Tommy Wood 56:55 So everybody ... You know, the first thing that happens when I talk about muscle mass is people are like, "Well, I don't wanna look like, don't wanna look like you."

Dr. Rangan Chatterjee 57:02 [laughs]

Dr Tommy Wood 57:02 And, like, that's fine. That's great. You don't have to. Um, and you basically just have to be in the top 50% of the population, right? So if you go out and you find 10 people like you, if you have ... If you're in the top half in terms of the amount of muscle mass, then you're good. That's enough.

Dr. Rangan Chatterjee 57:19 So that, that's the challenge to the listeners at the moment, right?

Dr Tommy Wood 57:21 That's the challenge.

Dr. Rangan Chatterjee 57:22 Find 10 people who are like you-

Dr Tommy Wood 57:23 Yeah

Dr. Rangan Chatterjee 57:23 ... and have a press-up competition.

Dr Tommy Wood 57:24 Yeah, exactly. And if you're s- if you're, if you're in the top half in terms of the number of press-ups you can do, then you're fine. Um, you don't have to do that. But ... So what does it take to achieve that kind of, um, some- something like that? And it's, it's really not very much. Um, if, if you've never done any kind of resistance training, and I ... Resistance training, I mean, uh, it could just be, uh, body weight stuff, so some of the things from your books, uh, like your kitchen workout. Uh, it can ... You can use bands. Yes, you can use weights and go to the gym, but you don't need to. Um, uh, this morning, I w- I watched a talk by Professor Sir Muir Gray, um, who, who was talking about, um, the healthiest thing to do with, uh, bags of sugar is to use them as weights.

Dr. Rangan Chatterjee 58:06 [laughs]

Dr Tommy Wood 58:07 And I was like, great. Yeah, you could ... So you could use bags of sugar, you could use, like, cans of beans, um, that provides resistance. And if you do, um, two to three sets per muscle group, right? So maybe you have to do bicep curls and squats and a press to, like, cover all your, your, your, your muscle groups. Two to three sets per week is probably enough.

Dr. Rangan Chatterjee 58:28 Two to three sets per week?

Dr Tommy Wood 58:29 Per week. So the minimum effective dose to, to increase strength is somewhere between two and four sets per muscle group per week.

Dr. Rangan Chatterjee 58:38 And when you say sets, is that 10 b- bicep curls? Is that 5?

Dr Tommy Wood 58:42 Yeah.

Dr. Rangan Chatterjee 58:42 Is it 15? What ... How do we define a set?

Dr Tommy Wood 58:45 So that's a great question, and the ... Again, what's really great is the answer is it, it doesn't matter-

Dr. Rangan Chatterjee 58:52 [laughs]

Dr Tommy Wood 58:53 ... as long as you go to something approaching what we call voluntary muscular failure, which is basically, "This is really hard. I can't do anymore," right? So if you pick ... If, if whatever you're doing, you can do five, and you're like, "I can't do six," then that's enough.

Dr. Rangan Chatterjee 59:10 Mm-hmm.

Dr Tommy Wood 59:11 But if whatever you're doing, you can do 30, but you can't do 31, then that's enough.

Dr. Rangan Chatterjee 59:16 Right.

Dr Tommy Wood 59:16 So it just has to get to a point where it gets hard enough that you say, "I probably can't do anymore." Um, and you don't need to, like, really push it and, like, get to the point where you're like, you know, yeah, your form looks terrible 'cause you're sort of, like, trying to muscle this thing up. You don't need to do that.

Dr. Rangan Chatterjee 59:30 It's the same principle as doing something new, isn't it? You're just saying maybe 20 to 30 minutes-

Dr Tommy Wood 59:35 Yeah

Dr. Rangan Chatterjee 59:36 ... on something that you find challenging, but then it's probably enough after-

Dr Tommy Wood 59:40 Yeah

Dr. Rangan Chatterjee 59:40 ... 20 minutes or so.

Dr Tommy Wood 59:41 Yeah.

Dr. Rangan Chatterjee 59:42 It's a similar kind of principle with the muscle.

Dr Tommy Wood 59:44 Yeah, exact- And so 20 minutes, two or three times a week, and even if it's just one set each time, where in that cho- in whatever you're doing. So say you're doing, uh, some squats, and, and if you can't do squats, then you could just do, like, sit ... You know, getting up and down from a chair, right? If that's the limit. And if you get up and down from a chair-

Dr. Rangan Chatterjee 1:00:03 Sorry to interrupt. If you're enjoying this video and want to learn more, you can download my free special guide containing six simple breathing practices that will help you calm your mind, lower stress, and improve your energy. To get ahold of this guide, all you have to do is click on the link in the description box below

Dr Tommy Wood 1:00:23 ... 15 times, and you're like, "Oof, I probably couldn't do a 16th," then that's great that you've ... That's all you need to do.

Dr. Rangan Chatterjee 1:00:27 Yeah, I, I think the important message there is for people ... 'Cause people tend to get hung up on numbers a lot of the time.

Dr Tommy Wood 1:00:31 Yeah.

Dr. Rangan Chatterjee 1:00:31 Is it 10? Is it 15? Is it five?

Dr Tommy Wood 1:00:33 Yeah.

Dr. Rangan Chatterjee 1:00:33 It's like, no, it's voluntary muscular failure.

Dr Tommy Wood 1:00:35 Yeah.

Dr. Rangan Chatterjee 1:00:35 So ... And that's gonna change as you get stronger.

Dr Tommy Wood 1:00:39 Yeah.

Dr. Rangan Chatterjee 1:00:39 Right? So maybe it's you can do f- only two press-ups now, but as you get stronger, it'll be, you know, five is what you need to do.

Dr Tommy Wood 1:00:47 Yeah.

Dr. Rangan Chatterjee 1:00:47 And as you get stronger, it's gonna be 10.

Dr Tommy Wood 1:00:48 Yeah.

Dr. Rangan Chatterjee 1:00:49 Yeah. So that's the minimum effective dose.

Dr Tommy Wood 1:00:53 Yeah.

Dr. Rangan Chatterjee 1:00:53 Okay? So the premise is we're trying to maintain our brain health as we get older. Uh, above the age of 30, we start to lose muscle mass. You're making the case that lean muscle mass is very important for our cognitive health and many other aspects of our health.

Dr Tommy Wood 1:01:08 Yeah. Yeah.

Dr. Rangan Chatterjee 1:01:08 So you're saying the minimum effective dose is two to three sets on- Most muscle groups-

Dr Tommy Wood 1:01:14 Yeah

Dr. Rangan Chatterjee 1:01:15 ... a week. So that's gonna do something, that you're gonna get benefit from that.

Dr Tommy Wood 1:01:19 Yeah.

Dr. Rangan Chatterjee 1:01:20 You've given us the minimum effective dose, but presumably more, up to a point, I guess, can be better?

Dr Tommy Wood 1:01:28 Yes. And so what I think is the ba- like the best balance of, like the amount of response you get versus what's practical for most people, is probably something more like eight to 12 sets per muscle group per week, split over two to three sessions. And so it's very common in the exercise literature to see three times per week, three sets per muscle group, and then, you know, they usually do like something like eight to 12 reps-

Dr. Rangan Chatterjee 1:02:01 Yeah

Dr Tommy Wood 1:02:01 ... and, and, and, uh, change the weight to, to get it so that by, you know, 10 or 11, you're at that point of failure. Like, whatever that is for you.

Dr. Rangan Chatterjee 1:02:09 Yeah.

Dr Tommy Wood 1:02:10 So that's... And that's very common. And so there was, um... They've, they've done studies where they've compared individuals in their 70s versus individuals in their 20s, and with that kind of training protocol, so three times a week, three sets per muscle group maybe, so maybe six to eight different exercises each time. Even individuals in their 70s, you know, are gaining significant muscle mass, significant strength, right? So again, it's, it's not this thing you can't do it, right? The body still responds, it still adapts. Once you've achieved whatever level you want to achieve, you need much less to maintain it, right? You can maintain it with those levels we were talking about before, two or three times per week.

Dr. Rangan Chatterjee 1:02:47 Mm.

Dr Tommy Wood 1:02:47 Uh, whatever you've built up. Um, so that's important, too, right? Maybe you get to a certain point and you're like, "Well, I only just wanna maintain my strength." You need much less to maintain that you need-

Dr. Rangan Chatterjee 1:02:56 Mm

Dr Tommy Wood 1:02:56 ... than you need to actively build, so that's important, too. Um, there's a, there was a very nice study, uh, called the SMART, the SMART trial, where they did... gave people either resistance training or cognitive training or both, and they looked at sort of function and, and, um, uh, and things g- uh, like structure of the brain. They were looking particularly at the brain. And these, again, individuals in their 70s, and the resistance training protocol, which significantly improved function and structure in some areas of the brain, 'cause we were talking about the brain, was just that. It was three times per week, uh, three sets of six different machines in the gym. So you could go to your local, you know, local gym. You just do like some kind of row, some kind of press, a leg press, right? Five or six different machines, three times a week, three sets of eight to 12 for each, and then that showed significant benefits in the brain. Each session was close to half an hour. So it's 90 minutes a week.

Dr. Rangan Chatterjee 1:03:52 Very doable.

Dr Tommy Wood 1:03:53 Yeah.

Dr. Rangan Chatterjee 1:03:54 Is there any benefit for our health when we drink alcohol?

Dr Tommy Wood 1:04:00 No. Um, but as with everything, and I imagine most of the topics we'll talk about today, there are always caveats. So if you look at hard health outcomes, there's some mixed results and mixed research. And what previously we thought was that moderate alcohol consumption, so within, say, the alcohol guidelines, um, was associated with, with better health outcomes overall. So not drinking alcohol is less good for your health than, than drinking some. Um, when you then sort of break out the diff- the different health conditions, um, you might see that s- a small amount of alcohol intake or regular alcohol intake is associated with lower risk of cardiovascular disease, but then that's balanced by a slightly higher risk of certain cancers. So overall, if your main outcome is, say, how long do you live, there doesn't really seem to be any, any effect, uh, of, of alcohol, uh, either, either beneficial or, or negative in terms of moderate consumption. If you try and then figure out, well, what's a, a safe amount to consume, uh, there are several studies and, you know, me, I'm particularly interested in the brain, so there was a, a recent study that looked at brain volume, so the size of people's brains, which is... which decreases over time, that's associated with risk of cognitive decline and dementia. And a drink once a week seemed to be just fine, but beyond that, you maybe start to see some, some detrimental effects.

Dr. Rangan Chatterjee 1:05:34 Are you saying there, Tommy, that our brain volume will decrease over time as we get older, but that more than one drink a week, potentially one alcoholic drink a week, increases that?

Dr Tommy Wood 1:05:47 So when you look at these kinds of data, they're generally not longitudinal, as in they don't look at the same person over time. What they do is they look at people across ages and across levels of drinking, and at one snapshot in time, they say, "How much do you drink? And what does your brain look like?"

Dr. Rangan Chatterjee 1:06:07 Oh, so it's not the same person they're tracking.

Dr Tommy Wood 1:06:08 It's not the same person. So we kind of... So we cannot say that, um, alcohol is the driver here. Uh, when you do this kind of epidemiological research, we call it an association, right? This amount of alcohol is associated with these changes in the brain, but we don't know if it's truly causal. Um, we can adjust for a whole... But that's what we do with statistics. We adjust for other things that may be accounting for that, and then we, we think whatever's left is a signal. So, so I think that there are a few studies that basically suggest that drinking one or two drinks one or two times a week is probably fine, but anything above that, there's certainly no benefit, and then it may be detrimental to our brain health and our, our other health. The other side of that, though, is that, um, often people drink alcohol in social situations, and that if it's helping to facilitate social connection, and it means, you know, you're going down the pub with your mates and you get s- spend time and, and, and talk with them, that probably offsets some of the, some of those effects. So it's not always black and white, good or bad. Um, but higher levels of drinking than that, uh, don't seem to be associated with improved health and may be associated with wor- worse health. Um, but there, you know, drinking some amount is probably just fine. Uh, but then context and other things are gonna be important as well.

Dr. Rangan Chatterjee 1:07:25 Yeah, I think you bring up some really interesting points. And it's kind of one of the reasons I wanted to have this conversation with you, is to try and bring that context and nuance that I think is often lost in the conversation around health these days. You know, everything's either good or bad.

Dr Tommy Wood 1:07:43 Yeah.

Dr. Rangan Chatterjee 1:07:43 Which diet is best? You know, is alcohol all good or all bad? It's like, well, hold on a minute, it kind of depends. And I agree that it's pretty hard to make a case that there's a physiological benefit to consuming alcohol, but I think we also have to acknowledge that many cultures have managed to drink small amounts of alcohol now and again-

Dr Tommy Wood 1:08:07 Yeah

Dr. Rangan Chatterjee 1:08:07 ... in the community.

Dr Tommy Wood 1:08:08 Absolutely.

Dr. Rangan Chatterjee 1:08:09 And they seem to have high rates of longevity-

Dr Tommy Wood 1:08:10 Yeah

Dr. Rangan Chatterjee 1:08:10 ... and minimal disease. So it's like everything, it's balanced, right? And you can look at the blue zones, for example, which are front and center of everyone's mind at the moment because of, you know, the Netflix show. And I know there can be some debates on various things [laughs] in the blue zones, but I think one thing we can say is that many of these populations, they do drink alcohol, but they're also doing a lot of other things very well that may counterbalance that, like low stress, nutritious foods, strong sense of community, and all these things. So yeah. I- if we say though, what are the negatives? If we, if we really try and address, okay, for someone who does drink, let's say more than that one drink a week-

Dr Tommy Wood 1:08:52 Mm-hmm

Dr. Rangan Chatterjee 1:08:52 ... and goes, "Well, I feel okay," right? You know, "I think I'm eating well, I'm moving my body well." Um, you know, but you're saying more than one drink a week may be problematic. How would you have them think about that? You know, are there some key things, for example, you'd say, "Well, just watch out for these three things, because this is what alcohol consumption can do-

Dr Tommy Wood 1:09:13 Mm-hmm

Dr. Rangan Chatterjee 1:09:13 ... if you're not careful"?

Dr Tommy Wood 1:09:15 It's really difficult to tease that out at those very moderate levels, you know, within, say, government alcohol guidelines, right? Because it's gonna be very subtle and you may not... there may not even be something that you can, you know, put your finger on and say, "That's definitely something that you n- you need to watch out for." Um, when you talk about the blue zones, they may, you know, some of them, they may drink red wine every day. But in general, portion sizes are much smaller than we would consider a, a-

Dr. Rangan Chatterjee 1:09:47 Mm

Dr Tommy Wood 1:09:47 ... glass of wine, say, uh, i- in the UK. Um, so it's probably even more moderate than, than we might think, and of course, all the other things that you mentioned, uh, come into play. So one, one thing that I see very frequently is people really don't want to give up alcohol.

Dr. Rangan Chatterjee 1:10:06 [laughs]

Dr Tommy Wood 1:10:06 And, and I, and I, I'm not here sitting saying that you should. Of course, you know, I, I, I do dr- I do drink, uh, uh, occasionally and socially. But you might think about, you know, what is it that alcohol is, is facilitating for you? Like, why has it become a habit, if it is a habit?

Dr. Rangan Chatterjee 1:10:24 Mm.

Dr Tommy Wood 1:10:24 And so if it's the socio- social aspect, then actually now it's much easier to get non-alcoholic cocktails, non-alcoholic beers. You can still go out and you can have that, that same kind of ritual with your friends or, or with yourself that gives you that feeling of relaxation even though there's no alcohol involved. So you can get all of those benefits. You can still feel like you're getting that de-stressing at the end of the day with like a beer in front of the TV or something like that. Um, all of that is still, is still possible. Um, and so you can think about maybe re- replacing those things in, um, occasionally. And then it's also worth thinking about, often when people sort of fight against the idea that may- maybe they may be drinking too much, often we, we hear about... that it's like they're bargaining. "Oh, but I do all these other things, so isn't it okay that I drink alcohol?" And I'm not here to, to judge-

Dr. Rangan Chatterjee 1:11:15 Yeah

Dr Tommy Wood 1:11:15 ... one way or the other, but it's just worth thinking about. Like, are you trying to find ways to justify it? Um, and if you are, then that maybe signifies that that's worth thinking about even deeper and, and, and maybe considering some alternatives.

Dr. Rangan Chatterjee 1:11:30 Yeah, I really like that approach. One thing I think about with my patients who are in this conundrum is I, I always talk to them about their sleep.

Dr Tommy Wood 1:11:37 Mm.

Dr. Rangan Chatterjee 1:11:38 Because I think alcohol, for many people, disrupts their sleep, and often they're not aware of it.

Dr Tommy Wood 1:11:45 Yeah.

Dr. Rangan Chatterjee 1:11:45 You know, if they get this sleep fragmentation, they're waking up multiple times in the night, they don't always know that. They just know they feel tired the next day.

Dr Tommy Wood 1:11:53 Mm.

Dr. Rangan Chatterjee 1:11:54 And I've found that some people don't always put that together-

Dr Tommy Wood 1:11:56 Yeah

Dr. Rangan Chatterjee 1:11:56 ... with alcohol the night before. So I know with certain patients I've said, "Why don't we try a week without, just see how you feel?" And sometimes they'll go, "Wow, I've got so much energy and I'm sleeping better."

Dr Tommy Wood 1:12:06 Yeah.

Dr. Rangan Chatterjee 1:12:06 And then that's empowerment, 'cause I'm very much like you, Tommy. I don't really want to tell people what to do with their lives. I don't think it's my place to. And I think alcohol now is becoming the, again, a big thing that we're talking about in the public health arena, for good reason, because many people do have a problematic relationship with alcohol. But I think we've got to be very careful it doesn't go to nobody should be drinking ever.

Dr Tommy Wood 1:12:30 Yeah.

Dr. Rangan Chatterjee 1:12:30 I personally don't really drink much anymore. I don't think I've had an alcoholic drink in maybe four or five years now. And I have no ethical or moral problem with people who do at all. It's just in my own life, I've found I got to a point where I just don't need this anymore.

Dr Tommy Wood 1:12:45 Yeah.

Dr. Rangan Chatterjee 1:12:45 Like, it's not doing anything for me, and I prefer the way I feel without it. So yeah. I don't know, anything else you want to add on alcohol perhaps?

Dr Tommy Wood 1:12:53 Yep. From my own personal experience, I notice that it affect, negatively affects my sleep. That's one of the reasons why I don't drink very regularly, you know, maybe once a month or something, because I certainly feel less well-rested the next day. It, it, um, affects your temperature regulation, so you're like, like hot during the night or other things. You just don't feel as, as, as, as rested. So that, that certainly, uh, that's a nice in because I, I think that's something that the people will, will appreciate, that that's gonna be important and they'll notice the difference.

Dr. Rangan Chatterjee 1:13:21 And may I ask, given that you know it affects you negatively, 'cause this is the funny thing about alcohol I think, we, we all know, I know when I was drinking, that you're gonna not feel good the next day.

Dr Tommy Wood 1:13:33 Yeah.

Dr. Rangan Chatterjee 1:13:33 Or you're not gonna be your best self the next day, yet we still do it.

Dr Tommy Wood 1:13:35 Mm.

Dr. Rangan Chatterjee 1:13:37 I guess it's a bit of a personal question, but given that you know all that, and I kind of ... I'm asking this just for the purpose of asking it rather than, you know, trying to highlight anything because, you know, we're all human.

Dr Tommy Wood 1:13:49 Mm.

Dr. Rangan Chatterjee 1:13:50 Given that you know it's gonna negatively affect your next day, what goes through your mind before you actually consume it?

Dr Tommy Wood 1:13:58 So I've ... Historically, I, I've, I've struggled with a lot of these things around alcohol. I had what some people might have considered disordered eating a long time ago, and being very hyper-focused about the quality of the food that I ate and, and, and what I ate. And so it's taken me a long time to work on some of those things. And in reality, I've g- gotten to a point where I'm ... where if I've decided to do it, then I lean into enjoying it. So if I'm gonna eat this cake, I'm gonna enjoy this cake.

Dr. Rangan Chatterjee 1:14:29 Yeah.

Dr Tommy Wood 1:14:29 Like, this is, you know, I'm ... Or all, and all the reasons why, why I'm eating it, just, like, if I'm gonna have a nice cocktail, I'm gonna make sure it's a, it's a nice cocktail. I'm really gonna enjoy it. I'm with my friends.

Dr. Rangan Chatterjee 1:14:39 Yeah.

Dr Tommy Wood 1:14:39 I'm having a nice dinner. So I really lean into, um, the enjoyment factor because the, the alternative is spending hours then worrying about the thing that I ate or the thing that I drank and how that's gonna affect my health, and that worrying is probably worse than the-

Dr. Rangan Chatterjee 1:14:53 Yeah

Dr Tommy Wood 1:14:53 ... eating and drinking itself. So I embrace the, the positive sides of it because, you know, it's usually a social aspect or so-

Dr. Rangan Chatterjee 1:15:00 Yeah

Dr Tommy Wood 1:15:00 ... or some other thing. And then, uh, and I think that's, that's how I approach it.

Dr. Rangan Chatterjee 1:15:04 Yeah. Love it, Tommy. Thank you for sharing that. Okay. Let's move on to caffeine.

Dr Tommy Wood 1:15:07 Uh-huh.

Dr. Rangan Chatterjee 1:15:08 Okay. There's plenty more I could do on alcohol.

Dr Tommy Wood 1:15:09 [laughs]

Dr. Rangan Chatterjee 1:15:09 But I think I'm gonna try and discipline myself to keep moving through topics today. Caffeine, good or bad for our health?

Dr Tommy Wood 1:15:19 Uh, yes. [laughs] Um, as, as ever, and I think this is gonna happen several times, the, the answer is, uh, it depends. Um, there's ... Certainly if we go back to the, uh, epidemiological observational evidence where you ask people how much coffee they drink and then you look at their health outcomes, it seems like drinking up to, you know, three or four, maybe more, small cups of coffee, so, so probably, like, one or two of my cups of coffee, um, per day, is associated with, um, improved health outcomes, and that's, uh, liver disease, Alzheimer's disease. Um, and then, um, there's certainly no, no signal of harm, right? So it, it doesn't seem to be harmful up, up to those levels, and, and, and maybe some benefit. Of course, there's no randomized controlled trials of coffee drinking that, that show that definitively. Um, but there does seem to be some potential benefit there, and there's, there's lots of, um, polyphenols and other things in, in, say, coffee, for instance, or, uh, or tea. Um-

Dr. Rangan Chatterjee 1:16:20 Could you just explain what a polyphenol is-

Dr Tommy Wood 1:16:21 Yeah

Dr. Rangan Chatterjee 1:16:21 ... for someone who doesn't know?

Dr Tommy Wood 1:16:22 Yeah. So these are the compounds, often they're colorful, that make up these beans or berries, and it's the same ... They're in the same class of compounds that make, like, blueberries blue. But they have, um, uh, coffee has its own, um, compounds like that, that seem to affect our gut microbiome. Uh, they affect our vascular health. And there are randomized controlled trials actually on some of that. They extract those polyphenols out, and they give them to people and look at their cardiovascular function or their, you know, their, uh, the health of their blood vessels or their cognitive function, and they seem to be beneficial. So, um, those are the kinds of things that are coming along for the ride, uh, with caffeine. But sometimes, uh, when you look at the research, like decaf coffee for instance doesn't ... has some of the benefits, but maybe not all of the benefits of, of, uh, caffeinated coffee. But again, you have to think about, well, what kind of person drinks decaf versus regular coffee? And it's probably the differences in those people that's driving that rather than the caffeine itself. So I think there's definitely a signal that some caffeinated beverages, uh, you know, may be associated with improved health outcomes, and that's probably 'cause some of the compounds that come along for the ride in those, both tea and coffee separately. But then you have to think about the other side. So what are the things that caffeine can potentially negatively affect? The most obvious one is, is sleep. And different people have different, uh, abilities to metabolize caffeine. So there's a gene, uh, that, that affects how fast you metabolize caffeine, and anybody who's done a genetic test will have probably gotten that on there-

Dr. Rangan Chatterjee 1:17:52 Yeah

Dr Tommy Wood 1:17:52 ... and know if they're a fast or slow metabolizer. And there's some early evidence that suggests that people who are slow metabolizers that drink a bunch of caffeine may be getting some negative, uh, effects of that just 'cause it's hanging around in their system for, for much longer. Um, but you probably know that a little bit about yourself anyway, or a lot of people do. So I, you know, I know some people who are very sensitive to caffeine, right? They have any at all and they're awake for 24 hours.

Dr. Rangan Chatterjee 1:18:16 Mm.

Dr Tommy Wood 1:18:16 They can't sleep. Whereas, um, others ... And then, uh, again, it becomes, you know, you don't know what's habit versus real, but some people who say, you know, "I can drink caffeine late at night, and it doesn't affect my sleep at all." We don't really know if that's necessarily true. But it's certainly ... There's, there's some good evidence from, uh, randomized controlled trials. There's a meta-analysis that came out, um, in the last year or two that, that looked at caffeine intake, and it can affect sleep architecture and how much sleep you're getting.

Dr. Rangan Chatterjee 1:18:42 Negatively.

Dr Tommy Wood 1:18:43 Negatively, yes. So then it's just a case of making sure that you're timing your caffeine relative to your sleep so that it doesn't negatively affect your sleep. Um, so for me, I try not to drink caffeine after midday. Because there was this period of time where I was having coffee, you know, every night and, you know, we're in the lab or ... and everybody's drinking coffee in the late afternoon. This is very ... I did my, did my PhD in, uh, in Norway, and it's very normal to have a cup of coffee at 4:00 in the afternoon or something. I couldn't figure out why I couldn't sleep. [laughs] Um, and then, then it, sort of tinkering with caffeine timing, that, that, that made a really big difference. But that's gonna be very personal from, from person to person, like how much, how much it affects them. The other thing that I think is very interesting about caffeine is how it affects cognitive function. And if you're doing very simple tasks or you're very sleep deprived, caffeine does seem to be beneficial. But if you consume a lot of caffeine, it can actually negatively affect your cognitive function, particularly on complex tasks. So it might improve your action time, but if you had to think through some complex task, and they, they do this in the lab with, like, complex executive function, like how, how, how fast-

Dr. Rangan Chatterjee 1:19:58 Mm

Dr Tommy Wood 1:19:58 ... can you interpret this diagram? Or how fast can you, uh, like, reel off these different things? Having a bunch of caffeine in your system can actually make you perform worse, and it's interesting because people think they're performing better, but they're actually performing worse. So caffeine, like, improves your mood, which we know it does, but it doesn't necessarily improve your performance.

Dr. Rangan Chatterjee 1:20:16 Yeah. It's so interesting. I mean, there's quite a few things to pick up on there. First of all, genetic testing. I like the theory behind the genetic testing of fast metabolizers to slow metabolizers. But what I've seen with certain people, and experienced myself, I think I am a fast metabolizer genetically-

Dr Tommy Wood 1:20:38 Ah

Dr. Rangan Chatterjee 1:20:38 ... but I'm exquisitely sensitive.

Dr Tommy Wood 1:20:40 Yeah.

Dr. Rangan Chatterjee 1:20:40 So I'm like, wait a minute, the genes are saying this, but I can be ... I've got to be very careful with my caffeine intake, both in terms of dose and timing. For many years, I won't touch caffeine after 12 o'clock midday-

Dr Tommy Wood 1:20:54 Mm-hmm

Dr. Rangan Chatterjee 1:20:54 ... unless there's some, you know, I'm, I'm tired and I'm s- I'm driving, right?

Dr Tommy Wood 1:21:00 Yeah.

Dr. Rangan Chatterjee 1:21:00 Or I really need to get through, knowing there may be a consequence that evening as well-

Dr Tommy Wood 1:21:04 Uh-huh

Dr. Rangan Chatterjee 1:21:04 ... but for, for whatever reason, I need to get through something. So that was the first thing to comment on. So-

Dr Tommy Wood 1:21:09 And I would just quickly respond to that by saying that whenever you think about any part of a biological system, it's not just one thing that's important.

Dr. Rangan Chatterjee 1:21:19 Yeah, exactly.

Dr Tommy Wood 1:21:19 Right? So, um, your caffeine and metabolism will tell you how far, like, well, it should tell you on average how fast you'll clear it. But caffeine attaches to a receptor. It's an, it's a, it's an ad- adenosine receptor antagonist, so there's gonna be polymorphisms in the receptors. There's gonna be differences in, in how you then respond to that, to caffeine binding to that receptor and what happens in the cell, and that's gonna be different from person to person as well. So yeah, you're right. Just that one thing isn't gonna be enough to tell you exactly how you're gonna respond to caffeine.

Dr. Rangan Chatterjee 1:21:49 Yeah, and I think also something I'm quite passionate about, whether it be alcohol or caffeine, is that I've noticed with patients and myself that the kind of stress load in your life also can play a role here. For example, I remember when I did use to drink, not to excess, but if I'd have a glass of red wine or a beer in midweek, let's say after work-

Dr Tommy Wood 1:22:11 Mm-hmm

Dr. Rangan Chatterjee 1:22:12 ... sometimes I wouldn't sleep so well, and you'd feel it the next day. You know, maybe one or two units of alcohol. But the same amount when I was on holiday, I wouldn't feel a thing.

Dr Tommy Wood 1:22:22 Yeah.

Dr. Rangan Chatterjee 1:22:22 Now, it could be, you know, different alcohol, but you know, it was kind of similar and I really thought about this. I thought, well, my stress load is right down. I feel I've got a lot of headroom psychologically and mentally as well. And I think, you know, I really think about this idea that I don't think we can completely separate biology and psychology. Like, I do feel there's something about us. If you're really, really stressed and you're using caffeine to get you through, I don't know. I, I, I really sort of believe there'll be a different impact-

Dr Tommy Wood 1:22:52 Yeah

Dr. Rangan Chatterjee 1:22:52 ... than if you're very relaxed and drinking it.

Dr Tommy Wood 1:22:55 Yeah, and caffeine partly activates the sympathetic nervous system, which, you know, the stress fight or flight side of your nervous system. So if you're adding, if you're pouring that on top of a whole bunch of other psychological stress, of course there's the potential for a greater negative effect. Like the context is, is important as well. Absolutely.

Dr. Rangan Chatterjee 1:23:15 Did you ever see the study, uh, I think it was in 2011 from the University of Bristol, where they looked at caffeine drinkers and they tried to really answer the question from recollection, does caffeine really enhance performance-

Dr Tommy Wood 1:23:29 Mm

Dr. Rangan Chatterjee 1:23:29 ... and ex- enhance our cognition? And the conclusion of that study was if you are a habitual caffeine drinker, then yes, consuming your caffeine in the morning does raise your mood and cognition, but only to the level of where non-caffeinated drinkers-

Dr Tommy Wood 1:23:47 Yeah

Dr. Rangan Chatterjee 1:23:47 ... are all the time. And I find that really interesting 'cause it kind of makes sense to me that for a lot of us that would be the case. That if we ... 'Cause in the past I have quit and I haven't had it for a few months, and I'm like, I feel great all the time.

Dr Tommy Wood 1:24:00 [laughs]

Dr. Rangan Chatterjee 1:24:00 Even I don't need a morning cup of tea or coffee, but I do enjoy it. So what is your perspective on that, and then how does that fit alongside the fact that athletes, for example, or I know you work in Formula One, for example, so I don't know if you encourage your drivers to maybe have caffeine or not. So-

Dr Tommy Wood 1:24:21 That's a, a very well cited study, the one that you mentioned. I think that's probably right, is that a lot of that first caffeine boost is just making up the, the caffeine deficiency that you've, you've [laughs] generated because you're so habituated to it, and that takes you up to sort of like your normal baseline. Um, and then you can, you can wean yourself off within a couple of weeks and that, that effect goes away. Um, the ... I think the f- the Formula One drivers, it's very different from, from driver to driver, but something that I've noticed over the years actually fits very well with what I was saying earlier. So there are multiple components to performing well in that environment. But if you think about, uh, the beginning of a Formula One race, there are two things you want to do. You want to get off the line as fast as you can.

Dr. Rangan Chatterjee 1:25:08 Mm.

Dr Tommy Wood 1:25:08 And you want to navigate the first corner while 19 other cars are trying to do the same thing. So caffeine, and this is based on the work of Yerkes and Dodson, uh, which looks at how, um, at your arousal level and your performance of, of tasks. And there's this, there's this classic arousal curve, which is basic- which basically says that the more aroused you are, the better you perform, up to a point where greater arousal is basically more anxiety and more stress, and then your performance goes down. And every sport has its own sweet spot-

Dr. Rangan Chatterjee 1:25:44 Mm-hmm

Dr Tommy Wood 1:25:44 ... for arousal. So if you're a sprinter in the blocks, your ar- your optimal arousal level is very different from a snooker player, right? Or a, or an archer.

Dr. Rangan Chatterjee 1:25:53 Mm.

Dr Tommy Wood 1:25:53 Even in the, even in the Olympics, right? The... So that's why, um, they banned beta blockers, which sort of calm down your nervous system in those sports where you wanna be, like, very calm, like, like archery, say, or, or some kind of shooting or snooker. Um, whereas-

Dr. Rangan Chatterjee 1:26:10 I think used to in the '80s-

Dr Tommy Wood 1:26:11 Yeah

Dr. Rangan Chatterjee 1:26:11 ... I think even they'd drink whilst playing snooker. I think they would-

Dr Tommy Wood 1:26:13 Yeah, because it would calm them down. Exactly.

Dr. Rangan Chatterjee 1:26:14 Exactly.

Dr Tommy Wood 1:26:15 Yeah. Um, for that reason. So they're adjusting their arousal curve. Um, but something like caffeine will im- improve your performance, um, in a simple cognitive task or a simple task. So particularly what the thing that they measure, measure is reaction time. It's often called a psychomotor vigilance task. So if you wanna get fa- if you wanna get off the line fast in a Formula 1 car, caffeine is great.

Dr. Rangan Chatterjee 1:26:39 Mm-hmm.

Dr Tommy Wood 1:26:39 Um, but what happens is that you can get to a point where your caffeine dose is so high, it will then affect your ability to navigate the first corner because all of a s- which is a much more complex cognitive task because you're trying to figure out the direction you're going, plus where all the other cars are. Um, and so you can, you can caffeinate ... You wanna caffeinate yourself to the point, and not all drivers use caffeine. This is the ... Like, some find some benefit from small doses at the right time. But you wanna improve your reaction time off the line, but you don't want to negatively affect your ability to then navigate the first few corners of the race. So there's a really fine line in terms of that arousal curve, and I've seen that in action in Formula 1 drivers, so I just th- think is really interesting.

Dr. Rangan Chatterjee 1:27:20 Yeah, absolutely fascinating. Even that idea that different sports have got different times where you want to peak.

Dr Tommy Wood 1:27:28 Yeah.

Dr. Rangan Chatterjee 1:27:29 And I guess then taking it back to a non-sportsman, well, we've all got different things in our lives that are important to us, and different times in the day when we want to peak, right?

Dr Tommy Wood 1:27:40 Yeah.

Dr. Rangan Chatterjee 1:27:40 So, you know, again, what's the right dose for you? What's the right time for it? Which I guess comes with experimentation.

Dr Tommy Wood 1:27:46 Yeah.

Dr. Rangan Chatterjee 1:27:46 And just trying to bring alcohol and caffeine together and sort of close them off, I guess what you're saying, and I would agree with Tommy, is that there's pros and cons, and we need to figure out what works for us. And if, for example, you really enjoy your caffeine, and it has no seemingly negative effects on your mood, your anxiety levels, or your sleep, and even if you accept that drinking it might just bring you back up to the level that if you didn't drink it, but you get so much enjoyment out of it, you know, I love a good cup of black coffee in the morning-

Dr Tommy Wood 1:28:22 Uh-huh

Dr. Rangan Chatterjee 1:28:22 ... for sure, then it's probably worth it.

Dr Tommy Wood 1:28:26 Yeah.

Dr. Rangan Chatterjee 1:28:27 But if you enjoy it and love it, and it's giving you palpitations and anxiety, and it's trashing your sleep, and you're moody and reactive with the people around you, you know, you might wanna rethink about your relationship with it, basically.

Dr Tommy Wood 1:28:41 [laughs]

Dr. Rangan Chatterjee 1:28:41 So it's not black or white.

Dr Tommy Wood 1:28:43 Uh, when you sort of bring them together, I think if you think about, uh, our collective modern lifestyles, that's a phrase that you use, um, what, what often happens is that you'll drink at the end of the day, then you'll need to ... You won't sleep very well. You'll have to drink coffee all day because you're sleep deprived. And then to wind down, you're gonna need alcohol at the end of the night. So they, they often reinforce one another. And so, again, it's just worth thinking about how is it, uh, affecting

Dr Tommy Wood 1:29:14 you. Is, is there ... Is it possible that there's this, this sort of perpetuating, perpetuating a cycle of one another that you can somehow try, try and break? And if it's not neg- negatively affecting you, you're still performing well, you feel good, great. You know, we ... Neither of us would recommend that you change anything. But it's, it's possible that they, they can go hand-in-hand in that way as well. When I think about, uh, building a healthy brain, that's essentially what happens when, when you're, you're a baby, both, uh, in the womb and, and, and then afterwards for, you know, two or three decades potentially. Then I think, well, how, you know ... So what is it, what do you need to make a, a healthy brain in the first place, and then what do you need in order to keep it healthy? And, and those things are often very similar. They are essentially the, the, the same thing. And there's always going to be a huge amount of interest in, in terms of how do we maintain cognitive function late into life because-

Dr. Rangan Chatterjee 1:30:08 Sorry to interrupt. If you're enjoying this video and you want to learn more, then do check out my free special guide, which contains the six crucial steps you need to take in your life to not only build healthy habits, but also to make them stick. If you wanna get ahold of this free guide, all you have to do is click on the link in the description box below

Dr Tommy Wood 1:30:30 ... age-related dementia and age-related cognitive decline are now the leading cause of death. Some people call it Alzheimer's disease, but there's, uh, Alzheimer's disease is, uh, as it was originally described, is probably a genetic early onset Alzheimer's disease. It might ... Uh, familial Alzheimer's disease. Whereas what most people have is this late onset Alzheimer's disease, which may actually not be the same thing. And it, and in my mind, it's a continuous, [laughs] um, onslaught, um, of the, of the brain from the environment, um, and then a lack of protective factors and a lack of protective inputs. So if you think about things that are protective and beneficial for, for the brain, so, so we've, we've talked about exercise. Um, I think the first time ... So first in, in rodents and then in humans, the first time we saw that we can actually increase the size of an important area of the brain later in life, uh, was the hippocampus. So the hippocampus is an area of the brain that's very important in memory. It's definitely, uh, affect- or is significantly affected in people with dementia, uh, or cognitive decline, Alzheimer's disease. And in an, an, uh, an older population, I think they were in their 60s, they had them just brisk- do brisk walking three times a week for a year. I think it was 45 minutes. And there was a control group who did some stretching for the same period of time. And in the brisk walking group... And again, when I, when I talk about cardiovascular exercise, aerobic exercise, that's what I mean. I mean going for a brisk walk. Like, it doesn't need to be more intense than that. But that group saw an increase in the size of their hippocampus, which would normally decrease in size with age. And it's the first time that we ever saw in humans, in adult humans, older adult humans, that an area of the brain can increase in size. And so exercise is incredibly important. Um, again, resistance training has similar effects, but seems to affect more, um, the white, the white matter, which is the part of the brain that's really, um, there for fast connection, sort of connecting all the different parts of the brain and sending signals. And, and so, so both aspects as we, uh, might separate them out, aerobic and strength, um, are, are important for the brain. And then the, the, the challenge aspects which we talk about, I think this is one of the probably the, uh, most, um, I guess forgotten important part of what it takes to make and keep a healthy brain. Um, a- and again, let's, let's use, uh, a- an athlete analogy, which is that if you stop training or for some reason you become immobilized, um, your muscles, a- and, and you have a, a good amount of muscle, you're an athlete, right? Or you, say, break your leg and it goes in a cast. When you take that cast off, you'll see the leg on that side is smaller. You've lost muscle mass on that side. So any time you stop, um, sort of giving an input, a stimulus to the muscles, they will reduce in size 'cause it's energetically expensive. If you don't need them, your body isn't gonna keep it, isn't gonna keep it around. And everything, all the evidence that exists today suggests that your-- the brain is the same, right? Use it or lose it. And when we think about using the brain, um, again, I, I like to compare back to what it takes to create and build a brain in the first place. So as an infant, you are doing things like learning to talk, learning social interaction, social cues, um, learning to control this fabulously complicated meat suit with incredible dexterity. And those things take a huge amount of, of neurological, uh, stimulus, input, and effort. Then throughout life, um, you may-- you start to do things that you may think are hard, but compared to that, really not that hard. Like biochemistry as an undergrad or learning to drive a car, um, or you know, the, the, the ins and outs o- of your job, right? They feel hard, but in terms of the stimulus and the, the, the effort required from your nervous system, it's actually quite small compared to, say, how-- learning how to control your whole body. And as we get older, we just do the same things again and again. They get easier for us. They just become habits. They become patterns which don't require, again, any significant cognitive input. And because of that, you're essentially telling your brain, "Hey, I don't need you to be as complex as you once were because we're not doing anything difficult." Um, and you see multiple different strands that, that, that kind of, um, come into this. So, uh, people have probably heard about the knowledge, right? London cab drivers. You know, less so now if, if, uh, if, if Ubers continues to be allowed to exist. But, uh, to be a, a, a black cab driver in London, you had to learn the knowledge originally, which is, um, all of the streets in a six-mile radius of Charing Cross. And they'd once looked at brain scans of people t- taking the knowledge or learning it before and after, and those who passed... And, and again, we don't know why they passed, whether it's because they were the ones who actually studied or, you know, they have some other, some other skills that allowed them to be able to gain the knowledge. Those who passed again saw an increase in size in certain aspects of the brain on a brain scan, and those who didn't pass the knowledge didn't become cab drivers, didn't. So you've, you've created this incredibly difficult stimulus which has then, you know, helped, uh, improve the brain. Um, and you see something similar in terms of people who retire earlier tend to die earlier as well. And that's after you adjusting for all the things that might cause you to retire earlier, such as medical conditions. So again, like telling the body, telling the brain that it's required, um, i- is incredibly powerful f- for brain health and, you know, we could go on. So if you look at the brain-- If you look at the brain health or the brain age of musicians, amateur musicians have a better brain age than professional musicians because amateur musicians, it's harder for them, right? They have to work harder to get, um, a, a, a nice result. So, so all of this is basically telling me that in order to keep your brain healthy, you need to tell, tell your brain that it's needed, and that requires you to do difficult things, which is gonna also require you to be bad at stuff as you learn new skills. Um, and then once you, once you've acquired a new skill, you then have to move on to something else. I mean, still do the thing if you enjoy it, but then as, as soon as something becomes habit, becomes patterned, becomes easy, it's no longer the same stimulus. So this could be anything. It could be dancing, it could be some kind of movement or sport. It could be singing. Um, teaching others, uh, seems to be, uh, pro- uh, protective as well. Uh, knitting. Um, I recently started to learn how to code on, on my computer because, you know, that was something that is beneficial for me, for my job, but also incredibly difficult. [laughs] I'd never done anything like it before. So there are all these things that you can do, uh, but you need some kind of ongoing stimulus, uh, to, to tell your brain that it, that it's still needed, it's still worth keeping around. Um, and, and, and that's something that, that you'll, you'll essentially need for as, for as long as you want your brain to, to still be working.

Dr. Rangan Chatterjee 1:37:57 I mean, it's so fascinating what you mentioned about the, the leg that goes in a cast, and six weeks later, muscle mass has, has declined. This whole idea that our brain is constantly responding to the inputs that we get. And if-

Dr Tommy Wood 1:38:13 Mm-hmm

Dr. Rangan Chatterjee 1:38:13 ... you know, if we think it's not required, it's, "I'm not gonna waste energy shoving it out. I'm gonna, I'm gonna focus on something else." But it, it made me think about something Professor Laurie Santos said to me recently on the podcast. She's from Yale, she's a psychology professor, and has, uh, got this globally successful course called The Science of Wellbeing, and she talks a lot about how our brains kid us often in terms of the things that are going to make us happy are not the sort of things that our brain think is gonna make us happy, so we actually behave in a way that actually isn't moving us towards happiness. And, and as you were talking there, it made me think that it's interesting that society, um, you know, the, the way we live now, you know, where, you know, everything's front-loaded as kids, and then we sort of just gradually decline once-

Dr Tommy Wood 1:38:58 [laughs]

Dr. Rangan Chatterjee 1:38:58 ... we start working. We don't have time anymore to try new things. It's just pay the mortgage, get to work, take the kids to their classes, and then you just... You know, people are waiting for retirement to-

Dr Tommy Wood 1:39:07 [laughs]

Dr. Rangan Chatterjee 1:39:08 ... just chillax. And it, and it sort of, it reminds me a little bit of that where, you know, as we're older, also we, we get, we get quite shy. We don't, we don't wanna suck at something. We don't wanna fail at something, so we don't do it. But what you're saying, Tommy, is that actually, that's exactly what we need to be doing. We need to be doing things that remind us that, "Hey, you are needed. My brain is needed. You need to grow. You need to respond." So, yeah. I mean, do you feel we're, we're sort of fighting human nature, or certainly the way society is set up, in an effort to improve our brain health?

Dr Tommy Wood 1:39:42 Y- yeah. Ab- absolutely. The, the way, um, society is, is set up is, is to sort of funnel you continuously in one direction, and then, you know, be, be very good at whatever it is that you do, but it doesn't require... A- again, it sort of becomes, you know, just part of the same thing again and again. It doesn't require the same, the same inputs. And I think there's a huge amount of benefit from, um, you know, being a bit of a jack-of-all-trades, you know, having lots of, having lots of interests, like diversifying your interests and your expertise and your skills. And that creates some buffer in terms of, you know, hey, w- you may not always have that job, or you may not always be able to do that job. You know, you know, having some kind of broader, you know, base of, of skills or things that you enjoy, uh, again, creates some, some kind of buffers in there. Um, but equally as, as we get older, we're expected to get more serious. Uh, another thing that I didn't mention, which is incredibly important, and, uh, very well, um, emphasized and advertised by our mutual friend Daryl Edwards, is play.

Dr. Rangan Chatterjee 1:40:53 Yeah.

Dr Tommy Wood 1:40:54 Adults aren't supposed to play. We're supposed to be serious. We're not supposed to have fun. Um, and, and again, it, it sort of, it become, you know, our, our exercise, our movement is supposed to be very prescribed. It's gonna be on a treadmill or you're gonna do X reps in the gym or whatever. And again, that's just not how we're des- how we, you know, quote-unquote, "designed to move." Like, we're supposed to be interacting with our environment, interacting with other people, animals, nature. You know, that's why our bodies are, are, are built and structured the way that they are. Um, but yeah, everything [laughs] that, that is required of us in, in modern-day society is sort of pulling us away, uh, from those, those stimuli, those inputs that, that our body, I think, expects, um, and, and then is what creates the foundation for, for long-term health.

Dr. Rangan Chatterjee 1:41:39 Yeah, and that, um... There's a brilliant talk that you did on brain health that's on YouTube, and I'll definitely link to that in the, uh, the show notes for, for this podcast. You put up a graph towards the end, and I think you... It's something about the amount of cognitive capacity it requires to do certain things and, and, you know, uh, one end was learning to walk, I think, and the other end was, you know, retirement and [laughs] and doing sudoku.

Dr Tommy Wood 1:42:04 [laughs]

Dr. Rangan Chatterjee 1:42:04 And it was, the contrast was really quite stark.

Dr Tommy Wood 1:42:09 Yeah. And you know, I, I, uh, so I borrowed that graph. I remade it. It was made by a friend of mine, uh, Dr. Josh Turknett, who's a neurologist, uh, over here i- in the US. And, you know, s- s- a l- a lot of those ideas about sort of this, the requirement of, of, uh, long-term, uh, stimulus to, to keep our brains healthy is, is certainly something that, that I've discussed a lot with him and, and, and gotten from him. And yeah, I mean, you... It, it's very difficult to quantify these things, right? Like, how could you possibly quantify the amount of effort that it takes to learn how to control the human body? Except for if you, you know, think about people, you know, adults who have to relearn how to walk or if you're trying to build a robot that's, that's, that knows how to walk, right? These are incredibly complex tasks that we haven't even necessarily been able to figure out yet, right? 'Cause it's that difficult. But most of the other things that we require of our brains can probab- you know, as adults, can probably be automated, um, to, to some degree because it's actually not that difficult. So, so yeah, if, if, if you think about what's re- what you, what you ask of your body and your brain, it, it just, it's just a steady decline throughout life. Um, and that requires now some kind of, um, significant effort on our part to, to, to prevent that.

Dr. Rangan Chatterjee 1:43:27 So in practical terms to people, that could be anything, right? That could be what? Learning a language, learning an instrument, um, I don't know, doing some balance work. You know, anything, I guess, where you're being challenged is going to have a positive impact on your current brain health, but also, I guess, make you more resilient for that sort of brain decline that we might see as we get older.

Dr Tommy Wood 1:43:55 Yeah, a- absolutely, and, and that's the thing is it can be- You know, almost anything that you en- I say you enjoy, but it's probably, if it's difficult, you're probably not gonna enjoy it to begin with, right? [laughs] This is what we talked about, we don't like being bad at things, and we t- you know, and we're sort of taught to feel like it's not good to be good at something. Whereas actually, if you think about kids, they will just try stuff, and they'll be bad at it, and they'll fall over, and they'll try again and again, and they'll get better over time. And that's, again, something that we need to, um, reacquaint ourselves with. Um, but then, you know, it, you know, it, it can and should be something that you enjoy doing, um, and that you can u- use, so you'd learn a language, and then one day we'll be able to travel again, and you can go and put it into practice. But it doesn't need to be a language. It could be anything, any of the things you mentioned. Um, and it, you know, could be, you know, knitting or, or whatever. Lit- literally anything that requires you to learn a new skill and that you enjoy. But again, as soon as you get good at it, you have to then start thinking, you know, what, what can I do next that, that sort of keeps the challenge going?

Dr. Rangan Chatterjee 1:44:56 Yeah. There's a, there's kind of conflict between mastery and, and super specialism-

Dr Tommy Wood 1:45:02 Mm-hmm

Dr. Rangan Chatterjee 1:45:02 ... with that kind of just general broad all-around knowledge, as you say, jack of all trades. And, uh, you know, you trained as a medical doctor. Um, I, I, I really do feel that, of course, specialism is important in medicine-

Dr Tommy Wood 1:45:18 Mm

Dr. Rangan Chatterjee 1:45:18 ... but I think we really have undervalued the role of the generalist f- for many years. And although not directly related to brain health, I can't help but see some similarities in terms of what you're talking about, and how we kinda need that overview. You know, I, I feel in medicine, Tommy, that now we need generalism more than ever. We've got all these complex problems that are, are coming across multiple systems in the body, and we can't just be focused on one organ. We have to be able to put everything together.

Dr Tommy Wood 1:45:50 Yeah, I agree. And when you think about people's health, I think the more that we learn, the more we realize how complex it is, how many different, uh, inputs, environmental factors are contributing to this disease or these symptoms in, in an individual patient. And if you're very hyper-focused on one system or one disease process, you're going to miss out, um, on all the, the factors that are, you know, sort of coming together, um, i- in this individual. So, so I think having a really, you know, broad base and open mind, uh, is really important when you're, when you're then trying to, um, because when you're then trying to improve the health of a patient because, like, the people can come in with the same, the same disease, um, the same concern, the same symptoms, and there could be vastly different, uh, underlying, uh-

Dr. Rangan Chatterjee 1:46:45 Yeah

Dr Tommy Wood 1:46:45 ... reasons, environmental, environmental, so- sociological, socioeconomic factors that, that could be contributing. Uh, and you really need to be able to appreciate all of those to get the best outcome.

Dr. Rangan Chatterjee 1:46:54 Well, I think that sort of approach applies to us looking after our own health as well, doesn't it? Instead of a laser-like focus in just one area, and, you know, we've both been in the nutrition space [laughs] for, for quite a number of years, and there can be a real focus on nutrition, and of course that's important.

Dr Tommy Wood 1:47:13 Mm.

Dr. Rangan Chatterjee 1:47:14 But there was, I think, for a period of time, a neglect of, uh, the importance of stress management, the importance of sleep. I mean, those things are starting to change, and if we, if we sort of think about brain health and how you think about it with your expertise, you mentioned some of the components of movement that can be really important. A- and I mean, before we move on from movements, just to, just to be really clear for people, you were saying in that trial, I think, that it was 40 minutes of walking, of brisk walking three times a week changed the size of your hippocampus, that, you know, one of the memory centers in the brain.

Dr Tommy Wood 1:47:51 Mm-hmm.

Dr. Rangan Chatterjee 1:47:52 We- that's not that much, is it?

Dr Tommy Wood 1:47:54 No, no, absolutely not. And again, I think, um, it comes, it comes from the, the, the way I believe society has, sort of, created this image of exercise, where, again, the pinnacle is the marathon. Um, and then to be fit requires this huge volume of running so that you could even survive a marathon. Um, but when we look at, you know, this is, you know, in terms of the brain, but also in terms of just, uh, overall mortality risk, you know, how long you live a healthy life, health span, you, you get to a point where you, you reach diminishing returns, you might call it. So, like, if you do a load more, you're not gonna get that much more benefit, and that point is something like 30 to 45 minutes of moderate to vigorous activity every day. Um, and when I say moderate to vigorous, I mean a brisk walk. 30 minutes of brisk walking a day is gonna get you the vast majority of the way, um, in terms of exercise that's required to see long-term health benefit, and if you do a load more, you, you, you're not gonna see that much more. So it's really not that much.

Dr. Rangan Chatterjee 1:49:00 It's not that much, and I, I really think this is a, this is a point that's worth hammering home. And, yeah, if we move on to nutrition, Tommy, in terms of what kind of things we should be eating to build a healthy brain. I'd be, I'd be interested in your view there. And also, I wonder if you could touch upon why a healthy brain's important, because it's, yeah, we wanna build a healthy brain, and then often we think about the other extreme, which is, oh, when our brain doesn't work when we're 70, or it doesn't work as well.

Dr Tommy Wood 1:49:33 Mm.

Dr. Rangan Chatterjee 1:49:33 But we forget that there's this long latent period where our brain function can start to decline before we even get symptoms. So just a couple of things there which I wonder if you could just sort of expand upon.

Dr Tommy Wood 1:49:45 Yeah, sure. So, so actually be- be- before we, um, get into that, you, you mentioned earlier about this hyper-focus on, on nutrition in terms of what's essential for, for long-term health. Um, and, and when I think about the things that a healthy body, a healthy brain requires long term, right? So nutrition is important. Um, but so is sleep or circadian rhythm, right? Light when it's light, dark when it's dark. Movement, um, s- some kind of stress mitigation, and then social connection. Probably those are the things that I think are gonna underpin most of the stuff. You know, those are the biggest rocks that, you know, that you can move to, to improve long-term health. Uh, I, I think that the more you neglect any one of those areas, the more you have to become hyper-focused in another. So-

Dr. Rangan Chatterjee 1:50:33 Yeah

Dr Tommy Wood 1:50:33 ... when people are talking about restricting, restricting, restricting from a dietary sense, and that could be total calories, it could be fat, it could be carbohydrates, it could be protein. All of them have been vilified, um, by different groups for, for essentially the same reasons. Um, I think that the reason why we had to become so hyper-focused and so restrictive to a large degree, um, and actually any one of those approaches c- can have ha- can have benefit depending on the person in front of you. Um, it's because we are neglecting the other things. We're neglecting movement, we're clept- neglecting sleep and, and circadian rhythm. We're neglecting social interaction, social connection. Um, and so, so that's, that's, that's one reason. It's also something that's very easy to sort of like quantify, whereas it's hard for me to say ... You know, it's easy for me to say, "Oh, you should stop eating carbohydrates." It's much harder for me to say, um, "Oh, you should go and make new friends," right? That's much harder. Um, and so I think that's one reason why we're hyper-focused. So the more you neglect the others, then you have to sort of like really sort of focus in on another one because those other systems are being, uh, uh, are not getting the attention, um, that, that they should. Um, in terms of building a healthy brain, um, I mean, the easiest way to, to think of it in my mind is, well, what is a brain made up of? Um, and it's mainly made up of fat and cholesterol. Um, and the, you know, th- that in our modern nutrition environment sounds very scary. I'm, I'm not telling you that you should, that you need to eat a whole load of fat and cholesterol. Actually, your brain makes its own cholesterol. Uh, the, the ... And it makes it from, from precursors that could be glucose or could be ketone bodies. When you're a baby, ketone bodies are essentially the preferred precursor for making new fats, making new cholesterol. Um, and but one of the, one of the things that's very important, um, is DHA, the long-chain omega-3 fatty acid that you get in seafood. And there's gonna be some variation in terms of what amount people need. Um, and it's probably going to be based on, um, their ancestral background. So there's some evidence to suggest that people who are of a more, uh, northern, um, ancestry, um, so people like me, uh, we got most of our, most of our long-chain polyunsaturated fatty acids from food, from seafood. So I'm probably gonna do better, uh, with more s- you know, direct from the source, whereas people who live close to the equator may have gotten more sort of precursors, like alpha-linolenic acid, which is the omega-3 that you might get in nuts and seeds, and then we make our own DHA. And there's a whole ho- whole host of other things, um, that can influence that. But there is gonna be some sort of individual variation. It's just the point that I'm trying to, trying to make. But DHA is incredibly important, and it's, um, accumulated very actively in the brain in the last trimester of, um, of pregnancy, so the last three months or so. And it's basically being actively, uh, depending on the amount in the mother, it's being actively regulated how much is passed on to the baby and then basically all of it is ending up, um, in the brain. And then some is put in the fat stores, um, and humans are the only primate that has significant fat stores when it's born, uh, and that's largely because it's a repository of these important things to then support the brain. Um, and again, because babies are born with an incredibly demanding brain, human babies, um, and it's, you know, we need these fat stores to support, to support it. It's one of the reasons that we have the brains that we do. So DHA is incredibly important. Um, lots of other things, you know, wi- will come up. So, uh, things like choline can be very important. Again, you might get that from eggs, liver, uh, organ meats, uh, potentially. Um, and then when I think long term, something that is probably having a negative effect on the brain is really large swings in blood sugar, and there's, there's a lot of data to support that. You know, if you're eating foods that cause very, very big spikes in blood sugar, that's probably over time going to have a negative effect on your cognition. And there are some studies that suggest that in people with diabetes, if you improve their blood sugar control, you improve their cognitive function, and this can happen over years. You know, and you ... And again, we're normally told that it's like this inexorable decline over time, whereas actually we have plenty of evidence to suggest that we can reverse that as long as we improve, uh, some of these factors. So, so it's just, um ... I think it's very positive and, and empowering to say, you know, wherever you are today, there is potential for improvement if you're, you know, sort of capable, a- able, and, and, and, and, and, you know, interested in doing that.

Dr. Rangan Chatterjee 1:55:30 But I think we do need to acknowledge maybe in this wellness community more than often does get acknowledged, that there are huge psychosocial stresses-

Dr Tommy Wood 1:55:39 Yeah

Dr. Rangan Chatterjee 1:55:39 ... cultural stresses for different communities, financial stresses, racial stresses. These things hugely impacts our biology and our physiology.

Dr Tommy Wood 1:55:48 Yeah.

Dr. Rangan Chatterjee 1:55:49 And for some of us it's easier to make those changes than for others, isn't it?

Dr Tommy Wood 1:55:54 Yeah. And I, I think it's, uh, it's been something that's sort of aimed at, uh, whether you c- you know, the lifestyle medicine or, uh, functional medicine or integrative medicine, uh, ancestral health communities. You know, those people who focus on these lifestyle factors that we've talked about. And it's a worthy critism- criticism to say- Not everybody can do that, right?

Dr. Rangan Chatterjee 1:56:15 Mm.

Dr Tommy Wood 1:56:15 Not everybody has the financial ability to remove themselves from the environment that they're in. If it's, you know, um, they have to live close to a road or they have to live close to a refinery, right? So in, in, in the, in the United States, um, you know, near, you know, large petrochemical plants, that's where you've had redlined housing areas where people from low socioeconomic status, usually more likely to be Black, have been put around these areas.

Dr. Rangan Chatterjee 1:56:38 Mm.

Dr Tommy Wood 1:56:38 And then it's, you know, it's baked into the environment and you can't afford to move out. Um, and, or it may be, you know, we talked about food, but, you know, what food to- do you have access to? Um, do you even have a kitchen? You know, do you have-

Dr. Rangan Chatterjee 1:56:51 Yeah

Dr Tommy Wood 1:56:51 ... are you working two jobs and you, you, do you have time to cook? Um, you know, we need to be very mindful that the social determinants of health play a big role here.

Dr. Rangan Chatterjee 1:56:59 Yeah. I, I mean, I totally agree with that. I, I think it's... I think there's a lot of nuance to that because sometimes that criticism gets leveled and say we shouldn't be giving any information out because it's not relevant to that community.

Dr Tommy Wood 1:57:11 Yeah.

Dr. Rangan Chatterjee 1:57:12 I don't agree with that.

Dr Tommy Wood 1:57:12 No.

Dr. Rangan Chatterjee 1:57:12 It's like we should definitely be giving out information, but we also need to be aware that that information may not be relevant or as relevant, and so we shouldn't look down when people can't take that advice, for example.

Dr Tommy Wood 1:57:26 Yeah.

Dr. Rangan Chatterjee 1:57:27 You know, and I've always fought for that, uh, wellness, for want of a better term, is for everyone. I think every single human being has the right to good quality health information that they can try and apply in their own life. And my bias comes from my clinical practice. So, um, I, I've worked in lots of different practice throughout my career, but there was a particular period of time where I worked in a practice in Oldham, in North Manchester, and it was a very low socioeconomic status area. Lots of immigrants, lots of people on benefits, people working two jobs, lots of single parents. A lot of, in inverted commas, struggle for day-to-day life compared to other areas I've worked where it's, um, you know, more affluent.

Dr Tommy Wood 1:58:13 Yeah.

Dr. Rangan Chatterjee 1:58:13 Now, there's struggle there as well in a different way. And you know what I learned, Tommy, in that, is that, because I think it's easy, and I see this in the media a lot, we... It's either we can empower people with their lifestyle choices, or we say that there's huge social determinants of health. It's kinda like, well, why does it have to be that black or white? I think all these things are nuanced-

Dr Tommy Wood 1:58:34 Yeah

Dr. Rangan Chatterjee 1:58:34 ... and I'm, I, I do passionately believe that this information is relevant for everyone, and we should be giving it to everyone, but with the acknowledgement that for some people it's harder.

Dr Tommy Wood 1:58:43 Yeah. And, uh, I completely agree. And I, in that line, I think it's very both patronizing and disempowering to say-

Dr. Rangan Chatterjee 1:58:52 Yeah

Dr Tommy Wood 1:58:52 ... that, "Oh, you shouldn't be talking about lifestyle or diet because it's, you know, these people, you know, may, may or may not have an ability to change that."

Dr. Rangan Chatterjee 1:58:59 It's very condescending.

Dr Tommy Wood 1:59:00 It's incredibly condescending. So but we just need to acknowledge that all of these things are important. Um, but again, there have been the, there was a, a recently published study came out in, in Lancet Public Health a few years ago that looked at using UK Biobank data, looked at like, uh, mortality risk, um, and they stratified individuals by some lifestyle factors. So based on quality of diet, whether they smoke, you know, physical activity, and then also stratified them by social deprivation. And you see that, yes, as your, um, like socioeconomic status decreases, overall risk increases.

Dr. Rangan Chatterjee 1:59:33 Mm.

Dr Tommy Wood 1:59:34 But when you look at the effects of lifestyle, movement, diet, there's still great benefit there.

Dr. Rangan Chatterjee 1:59:40 [laughs]

Dr Tommy Wood 1:59:41 So, so yes, the overall risk is greater, but you can, like those, there are individuals there, you know, reducing it through those, through those activities. So to say that we, we shouldn't be talking about it, I think is incredibly condescending.

Dr. Rangan Chatterjee 1:59:52 And, and also, you know, what I found, Tommy, is that if I change the advice I give them because I make that assumption, I'm depriving them of good quality advice. And what I learned there is actually sometimes in the poorest communities, they would actually literally follow my advice to the letter more-

Dr Tommy Wood 2:00:10 [laughs]

Dr. Rangan Chatterjee 2:00:11 ... than in more middle class affluent communities. Like I remember I thought, you know, there wasn't much money in the family and, you know, at the time I don't think we were allowed to give vitamin D. This lady had really bad pains, and I was convinced it was related and, um, you know, she went and bought from the local health food shop supplements for her and her family and got huge improvement and, like, it's unfair to, to think that we know what they will prioritize-

Dr Tommy Wood 2:00:39 Yeah

Dr. Rangan Chatterjee 2:00:39 ... with their money. It's not up to us. Yeah. I think this is, this is complex, but I think it's important that we talk about it actually.

Dr Tommy Wood 2:00:45 Yeah. A- a- absolutely. Um, uh, all of the, all of these pieces are, you know, different parts are, are important for different people in, in, in different amounts. And, um, there's, you know, part of it is just getting information out there and, and so, uh, again, empowering people to, to know what may or may not be important, uh, for them. For, and it could be whether they're worried about their risk of dementia or heart disease or, you know, they just wanna be able to play with their grandkids. Uh, you know, you know, often people's goals are much more practical than a doctor might think. You know, you're, you're worried about some diagnosis or something, but people, you know, wanna be able to just interact with their family or something like that. And different things are gonna be a different relative importance for different people, but they should be allowed to, to make those decisions.

Dr. Rangan Chatterjee 2:01:26 Yeah.

Dr Tommy Wood 2:01:26 And, you know, yes, we sh- I, I think that, um, we need greater support for behavior change for individuals who want it. Um, we don't necessarily-

Dr. Rangan Chatterjee 2:01:37 Sure

Dr Tommy Wood 2:01:37 ... do a good job of that.

Dr. Rangan Chatterjee 2:01:38 And doing something new that's stimulating and challenging, there are a lot of low cost ways to do that.

Dr Tommy Wood 2:01:43 Oh, completely free.

Dr. Rangan Chatterjee 2:01:44 If not free ways to do that.

Dr Tommy Wood 2:01:45 Absolutely. Yeah, absolutely.

Dr. Rangan Chatterjee 2:01:46 You know? Balancing, hopping around your... You know, I don't know. We could make up all kinds of things that would actually provide a stimulus.

Dr Tommy Wood 2:01:52 Yeah, absolutely.

Dr. Rangan Chatterjee 2:01:52 And, and so I think that's a great piece of practical advice. Okay, so that was in the first bucket. The second bucket was about important nutrients not getting to the brain, whether that be because we're not taking them in or because we're taking them in, or we might be taking them in, but they're not able to get to where they need to get because, let's say our, our blood vessels are in poor health for whatever reason. So you've been on a bit of a journey, Tommy, since I've known you and from what I've seen in public, um- As we have this conversation in 2022-

Dr Tommy Wood 2:02:27 [laughs]

Dr. Rangan Chatterjee 2:02:28 ... uh, what is your current viewpoint on nutrition for human health? Uh, I guess specifically we're talking around brain health-

Dr Tommy Wood 2:02:39 Yeah

Dr. Rangan Chatterjee 2:02:39 ... preventing cognitive decline as we get older, which I think everyone wants. What kind of advice would you give to people regarding foods?

Dr Tommy Wood 2:02:47 I think the, the starting point is that you should eat something that is accessible to you, that you enjoy, and is sustainable. Like, that has to be a, a starting point because I could give you a whole bunch of recommendations, but if it's none of those things, then you're not gonna do it or not gonna stick to it. And one thing that constantly fascinates me about the human body is how adaptable it is. Um, and the wide variety of diets that people, um, evolved while eating or, you know, ancestrally, you know, the, the different diets that, you know, my ancestors ate a very different diet to your ancestors just because of where they are on the planet, and they both thrived, and I find that fascinating. And so it, the, it's the same thing now, like, what somebody enjoys and is sustainable to them is very different from the person next to them, and they may sustain their health in, in an identical manner with, you know, objective, objective measures that you could take. So I don't have any particular one way that I would recommend that people eat, but it should support your health, and we can certainly talk about things that you might measure, uh, and want to, to track, um, over time. Specifically for the brain, uh, because we have interventional studies that, that show it's the case, um, B vitamins are incredibly important, so we're talking, um, B12, which generally you can only get from meat and animal foods. Um, if you are vegetarian or plant-based, I think the best people who, uh, promote or work with individuals with those diets would recommend you take a B12 supplement. Um, then, uh, folate, uh, uh, B2, which is riboflavin, and, uh, B, B6. Those are probably the most important, uh, nutrients for, for, for, for brain health. And again, you know, any diet that has a, a reasonable number of whole foods, plants, vegetables, eggs, meat, fish, will have enough of those probably. Um, then the other important thing specifically, uh, for the brain is, uh, uh, the omega-3s, long-chain omega-3s. And in this, in these studies that I mentioned earlier, uh, by David Smith, they showed that the greatest benefit from the B vitamin supplement came from those who had what they called adequate omega-3 status. And again, so these are long-chain, um, omega-3 fatty acids like EPA and DHA, which in the diet are generally only available from seafood. Uh, but there is a g- there is a slight genetic component based on people who can take shorter ones that you might get in chia seeds or walnuts and then convert them to, to longer chain ones. Um, but, uh, so again, there's, there's, there's a slight genetic component there, but some seafood is probably important as well.

Dr. Rangan Chatterjee 2:05:31 Yeah. Okay. This, this is super interesting. So you first mentioned B12, and as you say, if people are eating animal products in their diet, they're likely to be at least taking in enough B12. What I've found, wanting to measure this quite a lot, is that even people who were taking in reasonable amounts of B12 had suboptimal B12 levels on their bloods.

Dr Tommy Wood 2:05:58 Yeah.

Dr. Rangan Chatterjee 2:05:58 There's a whole variety of reasons why that might be. Uh, I have my view. I, I feel, I certainly feel stress is a huge part of it because to be able to actually absorb that B12, what needs to happen can be impaired, I think, by too much stress. Because I was thinking, why is it that they're eating enough B12 from what I can tell, yet that's not being shown up? And, and there's all kinds of reasons for it. That's just one of my views. I mean, what, what's your perspective on that? Is that something you've seen, and do you have any opinions as to the reasons why that might be?

Dr Tommy Wood 2:06:31 Yeah. Um, uh, absolutely. And I, I remember even, um, you know, 10 years ago, uh, it's now 10 years since I worked as a doctor pretty much, uh, as a junior, junior doctor at St Thomas' in London. I was working on the elderly care ward, and when people got a, a first diagnosis of dementia, even then one of the first things we did was, uh, something called a dementia screen, which we looked at iron status, uh, vitamin D, and some, uh, B vitamins, B12 and folate at least. And then if f- um, B12 was low, there was a second test they called methylmalonic acid, which is produced, uh, when you're B12 deficient. And so even then we were doing it in an NHS hospital 10 years ago.

Dr. Rangan Chatterjee 2:07:10 Yeah.

Dr Tommy Wood 2:07:10 Right? Just these basic nutrient sta- status checks. And I think, uh, stress is, you know, stress, um, certainly may affect, um, acid production, which is really important for B12 and also iron absorption. Um, but then some medications can do it. So metformin can, can affect B12 absorption. Uh, proton pump inhibitors, which people might take for, um, you know, reflux, that can affect, uh, B12 absorption, and these are very common drugs-

Dr. Rangan Chatterjee 2:07:36 Yeah

Dr Tommy Wood 2:07:36 ... uh, to prescribe. So, uh, you know, there's probably some, some lifestyle factors, but then, you know, it, it may also be a result of some- something else that somebody's taking.

Dr. Rangan Chatterjee 2:07:44 Yeah, I remember Professor Bredesen when I spoke to him about this a few, a few years ago. He, he will work with his patients to do all the tests, the homocysteine, the, the MMA that you mentioned, and the serum B12. And at the time, I remember thinking, "I, I can't get this stuff for my NHS patients back then." And he said he likes to see for cognitive function a serum B12, right? So that's your regular cheap, uh, B12 test. Um, and you know, I'm gonna say it depends on your lab, but, you know, the normal value that would be reported would typically be something like 200, 250 to 700, 800, maybe 900-

Dr Tommy Wood 2:08:26 Yeah

Dr. Rangan Chatterjee 2:08:26 ... depending on the lab.

Dr Tommy Wood 2:08:27 Yeah.

Dr. Rangan Chatterjee 2:08:27 Right? So huge, huge range of normal.

Dr Tommy Wood 2:08:30 Yeah.

Dr. Rangan Chatterjee 2:08:31 And he said in his experience, if it's under 600, he would treat it.

Dr Tommy Wood 2:08:35 Mm.

Dr. Rangan Chatterjee 2:08:36 And I remember I came back, 'cause I, I was chatting to him in America, and I, I tried that with a few patients actually, and again, this is just anecdotal. It's not a scientific study. But people would come back and say, yeah, they feel sharper. Their cognitive function has got better when I'd treat their serum B12 from, let's say, a normal level of 250. What do you think to that?

Dr Tommy Wood 2:08:57 I think that's, um... I mean, I'm, I'm not necessarily surprised. Uh, again, it depe- probably depends... What's interesting about, um, the difference between the US and the UK is that in the US you can't get an active B12 test, what we would call holotranscobalamin. It's very common to do in the UK. You can't do it in the US. So you, in, on the US test, you probably need to be at the h- at the upper end of normal because, um, there are lots of other things that can cross-react with the test, and they look like B12, but they don't have the function-

Dr. Rangan Chatterjee 2:09:32 Mm

Dr Tommy Wood 2:09:32 ... of, of B12. And that's the case with some, like, plant-based B12 analogues. Uh, so that, so for him, I, I imagine that's probably one reason why that may be the case. But equally, more broadly, I spent a lot of time, uh, looking at, uh, looking at and thinking about blood tests. And if we think back to what we said right at the beginning, which is that the average popula- the, the average adult has at least one chronic condition, takes at least one, um, medication, has at least one if not two of the components of metabolic syndrome, of which there are five. If that's the average person and the normal range is just... The way you define the normal range is you test a whole bunch of people and you take the middle 95%.

Dr. Rangan Chatterjee 2:10:17 Mm-hmm.

Dr Tommy Wood 2:10:17 And whatever the bottom, the lowest person of that middle 95% or whatever the top person is, that's the normal range. And if the average person is sick to some degree, then what's normal is not necessarily normal. Um, and I think that's part... And you, you see this again and again, um, that they've changed the ranges over time. That's been, uh, that's been the case for certain sex hormones, you know, like, and people have talked about this a lot. You know, they, they're decreasing the normal range for testosterone in men 'cause they think that testosterone is de- decreasing, um, on, at a population level. Whether it's actually true or not is up for debate. But it's something that's happened. That's, you know, they've changed the ranges if they see that, you know, the overall the population level changes. I saw something similar when they were trying to develop normal ranges for grip strength. Um, and what they saw over, you know, generations, you know, from, you know, like, uh, Generation X, uh, Generation Y, Millennials, like, uh, coming through to what w- in America we call Gen Z.

Dr. Rangan Chatterjee 2:11:18 [laughs]

Dr Tommy Wood 2:11:18 Um, grip strength was declining, particularly in males. So there was a publication that said that and said, "We need to change the normal range for grip strength," rather than saying, "We're getting weaker."

Dr. Rangan Chatterjee 2:11:28 [laughs]

Dr Tommy Wood 2:11:29 "Why aren't we working on that?" And so, you know, it's, it's like, um, the, the frog that sits in water from when it's cold, and then if, if you bo- if you boil it, it will slowly heat up. It will never jump out, right? 'Cause it never realizes-

Dr. Rangan Chatterjee 2:11:42 Yeah

Dr Tommy Wood 2:11:42 ... 'cause it's so incremental and slow. And so that's, that's one of the problems, is that we're look... You know, some normal ranges are constructed around a population that's sick, so then normal isn't necessarily, isn't necessarily normal, and that's p- that may be playing part of the role there, too.

Dr. Rangan Chatterjee 2:11:55 Yeah. It, it, it's super interesting, and hopefully we'll get time to go into some blood tests that people can do. You mentioned seafood. Why do you think seafood is so important for our brain health?

Dr Tommy Wood 2:12:06 Mm-hmm.

Dr. Rangan Chatterjee 2:12:08 And then for people who are vegan or, you know, choosing not to have animal products, can they still have good brain health and get those nutrients that you would get from seafood in other ways?

Dr Tommy Wood 2:12:25 So there are a few strands, um, the, the, the, of information that lead me to think that, that seafood... Or I say seafood because it's the, the most common dietary, um, component that gives us long-chain omega-3s. What I'm really interested in is long-chain omega-3s, particularly DHA in the brain. And again, if I go back to what does it take to build a healthy brain in the first place, DHA is preferentially sucked up into the brain while you're making it, as much that the mother will sacrifice her own DHA status so that the baby gets enough. Because it's one of the most critical fats that makes up the brain, for a number of reasons. Um, it, and it goes, it goes directly into the, the cell membrane. So people may or may not know that most of your brain, which is in water, is fat. Almost all of it, right? So, 'cause fat makes up all the, uh, insulation around the nerves. It makes up all the, the membranes around the cells. And DHA is incredibly important both for the function of the synapses, how they talk to each other, because of its, because of the, because of its structure. It has this, you know, very important, um, role in terms of, like, how the synapses work, how neurons talk to each other. But then it's also accumulated into the mitochondria, which people might know as the powerhouse of the cell. It sits inside the cell, generates most of the energy. And some of it is really cool physics that basically how electrons travel through DHA is really interesting. Um, but equally, you know, sort of like a more basic way, you can see that the more DHA that's in a mitochondria, the greater energetic capacity it has, the more energy it can produce. Um, and that's the reason why... And, and there are some evolutionary theories that say that, you know, maybe the human brain as it currently exists developed in a se- i- in, like, a group of hominids that had either di- direct access to lots of seafood or to the brains of other animals, uh, because brains are an incredibly rich source of DHA because your, your body preferentially shuttles it, uh, to the brain during development. So it has this really important functional role. Um- And when you, um, don't have it, that's associated with neurodevelopmental disorders or developmental delay, um, risk of other neuro- uh, like neurodevelopmental issues. Um, and then you can also see things like, um, there have been some interesting studies done in the UK and in the Seychelles where, uh, you look at the, the amount of seafood that a mother or her ba- uh, her children eat, and then you look at long-term neurodevelopment. And you, you asked about heavy metals earlier, particularly mercury is important for seafood. But it seems that even if you have a higher mercury burden because you eat a lot of seafood, you get a, you get greater benefit-

Dr. Rangan Chatterjee 2:15:10 Yeah

Dr Tommy Wood 2:15:10 ... uh, because of the omega-3s in the diet. Um, so that kind of, you know, that sort of first principles approach says, w- well, what does a brain really want when it's developing? And it really wants DHA. It's, you know, it's, it, it's essentially that's where all your DHA goes is, is your brain. And, and again, one of the things that, um, is interesting about humans is that we're the only mammal that has fat babies. No other animal has fat babies, and one of the reasons why, um, uh, human babies are fat is because they have adipose tissue as a store of DHA for the brain as it grows.

Dr. Rangan Chatterjee 2:15:49 When you say fat, you don't mean unhealthily fat?

Dr Tommy Wood 2:15:51 No, I mean, I mean like-

Dr. Rangan Chatterjee 2:15:53 Plump sort of-

Dr Tommy Wood 2:15:53 ... healthy, chubby, plump little babies, right? So if you look at any other mammal, um, when they're born, they're very lean, even other primates.

Dr. Rangan Chatterjee 2:16:02 Wow.

Dr Tommy Wood 2:16:02 They don't have large adipose stores. And what ... You know, it's, it's an en- so it's an energetic store, right? We know that adipose tissue, fat tissue is a, is a store for energy. But what ... But it also stores fats that are then particularly used for the brain, and D- DHA is one of them.

Dr. Rangan Chatterjee 2:16:17 So a developing brain needs it.

Dr Tommy Wood 2:16:19 Yes.

Dr. Rangan Chatterjee 2:16:19 Can we therefore say that a developed brain also needs it?

Dr Tommy Wood 2:16:26 So this is an exceptionally nuanced topic.

Dr. Rangan Chatterjee 2:16:31 Yeah.

Dr Tommy Wood 2:16:31 Even more so than any of the other topics that, that we've talked about. A colleague of mine, Dr. Rory Heath, and I wrote a paper recently about DHA and Alzheimer's disease. And some people have said that the DHA in, in patients with Alzheimer's disease, uh, in their brain is low. Others haven't quite found the, the, the same thing. Uh, part of it is probably that, again, your adipose tissue is, is essentially a very nice buffer of DHA that you can use across your lifetime. So it's, it's, it's quite ... If somebody is ... Unless somebody has never eaten seafood or has never eaten really any long chain omega-3s, it's very unlikely that you're gonna be deficient, um, in ... f- for the brain, for cardiovascular function, um, and, and other things that, that, that may not necessarily be the case. Um, and that's why the omega-3 index or, you know, how, you know, your omega-3s in your blood is a increasingly used, um, risk predictor of cardiovascular disease and things like that.

Dr. Rangan Chatterjee 2:17:21 Mm.

Dr Tommy Wood 2:17:22 Um, so it's, so it's, it's very nuanced. Um, but if you're going to be maintaining cell membranes and cell function, you're definitely gonna need some. And then the much better line of evidence comes from systemic measures of omega-3. It's impossible for me to measure how much DHA is in your brain, right? But I can measure how much is in your blood.

Dr. Rangan Chatterjee 2:17:41 Right.

Dr Tommy Wood 2:17:41 And when these studies were done at Oxford, they showed that you needed both adequate B vitamins and enough omega-3s in order for you to get this slowing in, in brain atrophy and cognitive decline. So if you measure omega-3 levels in people and they're low, they have a, a faster rate of cognitive decline, which tells me that that's important.

Dr. Rangan Chatterjee 2:18:03 Yeah.

Dr Tommy Wood 2:18:03 Because if you fix it, then you can, you can change that.

Dr. Rangan Chatterjee 2:18:07 Yeah. It's super nuanced.

Dr Tommy Wood 2:18:10 [laughs]

Dr. Rangan Chatterjee 2:18:10 Um, but it's super important because, you know, Tommy, one of the things that I've noticed is I have seen patients thrive on radically different diets.

Dr Tommy Wood 2:18:23 Yeah.

Dr. Rangan Chatterjee 2:18:24 So I'm like, there is no one true human diet that's for everyone, in my view.

Dr Tommy Wood 2:18:29 Yeah.

Dr. Rangan Chatterjee 2:18:29 It's just based upon 21 years now of clinical experience. It's like I, I, I, I've seen nothing to back that up. There are some principles, whole foods, uh, as much as you can, minimally processed, you know, decent amounts of healthy fats. There, there are some basic principles, but you can twist it in many different ways, culturally, ethically, you know, taste preference wise, using those principles to seemingly be in good health.

Dr Tommy Wood 2:18:59 I ... So I, I completely agree with, with everything that, that you've said, and I've also seen people thrive on an incredibly wide range of diets. Like I said earlier, I think that's one of the most fascinating things about humans, and we have to take individual health into consideration. And so lots of things are done at the population level that are very important. But if two different individuals can thrive on very different diets, and it supports their health in objective ways, and they feel good, we have to be able to support them.

Dr. Rangan Chatterjee 2:19:26 [laughs]

Dr Tommy Wood 2:19:27 And, and, and i- in doing that, um ... And to go back to omega-3s, like I don't ... If you don't want to eat seafood, there are algal, um, sources of long chain omega-3s, right? So you can do plant-based versions, absolutely.

Dr. Rangan Chatterjee 2:19:40 And you would recommend that to people?

Dr Tommy Wood 2:19:42 Um, I would recommend ... So I don't want to show up and just say people should take all these supplements. Ideally, you'd test, right? It's not difficult. I mean, an idea ... You know, in, in my perfect world, you would have access to this test through your doctor. It shouldn't be something you have to pay for, uh, because it's much cheaper than you getting a whole bunch of cardiovascular and cognitive diseases because you just didn't know that what you needed was a bit more omega-3, which would-

Dr. Rangan Chatterjee 2:20:09 So you would just ... You would, you would do one of those, what? Blood spot tests?

Dr Tommy Wood 2:20:11 Yes.

Dr. Rangan Chatterjee 2:20:12 That omega-3 test.

Dr Tommy Wood 2:20:12 You can do a blood spot for an omega-3 index. Um, and if you're in a good range, then don't worry about it. Um, if-

Dr. Rangan Chatterjee 2:20:18 So that's ... I think that's really empowering. It's like, look, if you're choosing to eat predominantly plants, you're choosing not to eat animal products, and you're maybe thinking about what Tommy just said and other guests have said in the past, thinking, "Okay. Well Why don't I just go and measure my levels?

Dr Tommy Wood 2:20:34 Yeah.

Dr. Rangan Chatterjee 2:20:34 That seems like a pretty practical approach to take.

Dr Tommy Wood 2:20:37 Yeah. And there are, there are some studies that have been done that have looked at the omega-3 levels, the DHA levels of, um, omnivores versus vegans, and sometimes vegans have lower levels, but there have been studies that showed no difference, right? So you can eat a plant-based diet and maybe you don't have any issues whatsoever. One, one thing that's interesting is that there may ... You know, I don't at this point believe in nutrigenomics, where you can measure your ... You can, y- you know, get a genetic test that will tell you the foods that you should eat. I don't think that we're at a point where we can do that. But one of the things that we know the most about is how our body metabolizes specific types of fats. Um, and there have been, there have been some studies that showed that if your ancestors became agriculturalists longer ago, right, so they were usually closer to the equator, usually became farmers, um, further away in the, in your- in our ancestral history, like more thousands of years ago, then the body has adapted to being able to take shorter omega-3s like, um, ALA, which you can find in nuts and seeds and some grains, and then turning it into these longer chain ones.

Dr. Rangan Chatterjee 2:21:46 Mm.

Dr Tommy Wood 2:21:47 By comparison, um, say, half, you know, half of my family is from Iceland, right? You can't grow grains in Iceland. Um, there's not a starchy carbohydrate to be seen anywhere, right? They ate seafood and they still do, and, you know, that was where they got their omega-3s, so their body's never had to adapt to it.

Dr. Rangan Chatterjee 2:22:05 Yeah.

Dr Tommy Wood 2:22:05 So there may be some people, and one of the reasons why they thrive on a completely, uh, p- plant-based diet is because they're really good at converting some of these precursors to the longer-

Dr. Rangan Chatterjee 2:22:16 Yeah

Dr Tommy Wood 2:22:16 ... chain, uh, omega-3s, and that's partly based on their ancestry and some other genetic components. So that's why I don't think that everybody who eats a plant-based diet should take an omega-3 supplement. I think they should test, and then if they need to change something, they should, but if they don't, then great.

Dr. Rangan Chatterjee 2:22:30 Yeah. If you enjoyed that, I think you are really going to enjoy this conversation about the most important things that you can do right now for your health and longevity.

Guest 2:22:40 If at 37 your limit is just being able to run that 30-minute park run, at 75 you're gonna have a very difficult time getting around